Highly purified human interleukin 2 and method

ABSTRACT

Interleukin 2 (IL 2; T-cell growth factor), produced with and without costimulation by Burkitt&#39;s lymphoma line Daudi, is highly purified approximately over 37,000-fold to apparent homogeneity from lymphocyte-conditioned medium derived from normal human blood cells by (NH 4 ) 2  SO 4  -precipitation, ion-exchange chromatography, gel filtration and hydrophobic chromatography. hp IL-2 is free of pyrogens, B cell inducing factor, B cell growth factor, interferon, CSF, and thymocyte differentiating factor. Nature IL 2 produced in the absence of Daudi cells has a molecular weight of about 26,000 daltons as measured by gel filtration and yields IL 2 having two molecular weights of about 16,000 and 17,000 daltons after denaturation as measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. IL 2 produced in the presence of Daudi cells shows a molecular weight of approximately 14,500 daltons as measured by both gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 
     This highly purified IL 2 is shown to correct immunodeficiency states in vitro and in vivo, especially in human patients. It shows value in the treatment of AIDS and immunodeficiency resulting from chemotherpy of cancer, as well as transplantation disorders such as graft versus host disease.

This invention was made with support in part under Grants CA 08748, CA22507, CA 25608, CA 20194, CA 21525, CA31525, P01-CA-20194, AI 18321-01, CA 23766 and CA 33050 awarded by the National Cancer Institute,National Institute of Health, DHEW. The government has certain rights inthis invention.

This application is a continuation-in-part of copending application Ser.No. 370,223 filed Apr. 20, 1982 and now abandoned.

Human interleukin 2 (IL 2; T-cell growth factor), produced in normalhuman blood with and without costimulation of Burkitt's lymphoma lineDaudi, is purified approximately 37,000-fold to apparent homogeneityfrom lymphocyte-conditioned medium by (NH₄)₂ SO₄ -precipitation,ion-exchange chromatography (diethylaminoethyl cellulose), gelfiltration (AcA 44 Ultrogel), and hydrophobic chromatography, preferablyon Blue Agarose and on Procion®-Red Agarose. IL2 can also be separatedfrom B cell growth factor (BGF) and B cell inducing factor (BIF) byhydrophobic chromatography or by a further step using high pressureliquid chromatography preferably in reverse phase. BIF is also known asT-cell replacing factor. (See Table I)

                                      TABLE I                                     __________________________________________________________________________    Purification of Human Interleukin 2                                                     Total  Total                                                                              Specific                                                          Protein                                                                              Activity                                                                           Activity                                                                              Purification                                                                        Yield                                     Fraction  (mg)   (U)  (U/mg protein)                                                                        (fold)                                                                              (%)                                       __________________________________________________________________________    I Ly-CM.sup.+                                                                           10,800 297,000                                                                              27       1  100                                       II                                                                              (NH.sub.4).sub.2 SO.sub.4 -                                                           9,000  247,000                                                                              27          84                                          precipitate                                                                 III                                                                             DEAE cellu-                                                                           135    183,000                                                                            1,356     50  62                                          lose(DE 52)                                                                 IV                                                                              AcA 44 Ultro-                                                                         40     145,000                                                                            3,625     135 49                                          gel                                                                         V Blue Agarose                                                                          0.96    87,680                                                                            91,333  3,382 30                                        VI                                                                              Procion.sup.R -Red                                                                    0.055.sup.++                                                                          55,229                                                                            1,004,164                                                                             37,191                                                                              19                                          Agarose*                                                                    __________________________________________________________________________     .sup.+ The IL 2 activity in the LyCM (lymphocyteconditioned medium) was       100 U/ml.                                                                     .sup.++ Protein concentration was determined by densitometric comparison      of the protein content in the samples with known amounts of protein           standards as detailed herein.                                                 *Use of HPLC is limited to those samples where there is incomplete            separation and/or trace materials are present.                           

Native IL 2 produced in the absence of Daudi cells has a molecularweight of about 26,000 daltons as measured by gel filtration and yieldsIL 2 having two molecular weights of about 16,000 and 17,000 daltonsafter denaturation as measured by sodium dodecyl sulfate-polyacrylamidegel electrophoresis. IL 2 produced in the presence of Daudi cells (10⁶/ml) shows a molecular weight of approximately 14,500 daltons asmeasured by both gel filtration and sodium dodecylsulfate-polyacrylamide gel electrophoresis.

This highly purified IL 2 shows a specific activity of about 10⁶ U/mgprotein which appears to be independent of molecular weight and anisoelectric point of approximately pH 6.7 for th 26,000 MW form andabout pH 8.1 for the 14,500 MW variant.

The highly purified IL 2 lacks detectable Interferon (alpha and gamma),granulocyte-macrophage colony-stimulating factor (CSF), T-cell replacingfactor (TRF or BIF), B cell growth factor (BCGF) and thymocytedifferentiating activity, and was free of any contaminating proteins asjudged by silver staining and by I¹²⁵ exolabelling in sodium dodecylsulfate-polyacrylamide gel electrophoresis. It is also pyrogen-free astested in rabbits. In this test doses of purified IL 2 were usedcomparable to the clinical doses tried (see below). Tests were done in 3rabbits/dose and little or no temperature rise is effected (LibercoTesting Corp, Roselle Park, NJ 07204 USP-XX). All four molecular formsof IL 2 were biologically active at concentrations of 10⁻¹¹ -10⁻¹⁰ M(0.2±0.05 U/ml), supporting the growth of human and murine cytotoxicT-cell lines.

In recent years, several functionally and biochemically unique solubleproteins have been discovered tht play a central role in regulating theresponsiveness of the immune system and/or act as antigen-non-specificeffector molecules capable of mediating one or more aspects of immunefunction. Most of these factors are synthesized by hemopoietic cells,especially lymphoid cells and monocytes, and are generally termedcytokines. Recent refinements in protein chemistry and separationtechniques, and the development of continuous cell lines secretingparticular cytokines, have made detailed cytokine analysis possible.

It was discovered that many of the cell interactions involved in theafferent arm of immune responses involved soluble helper or suppressorsubstances elaborated by these cells. These non-antibody mediatorsproduced by lymphocytes and other cells generated a degree of interestcomparable to that previously only given to antibodies themselves.

Today, there is hardly are area of the immune response concerning whichcytokine action has not been demonstrated or inferred.

Soon after the discovery that plant lectins stimulated the proliferationof human T-lymphocytes, soluble mitogenic factors were found in theculture supernatants. Since 1965, many such mitogenic factors have beendescribed, and, depending upon the assay used, as many different namesand acronyms were applied to the activities.

In 1976, it was reported that conditioned media from lectin-stimulatedmononuclear cells contained a mitogenic factor that would support thecontinuous exponential growth of lectin-activated human T-cells. Thisdiscovery allowed for the construction of a rapid, quantitative assayfor the T-cell growth factor (TCGF, IL 2), in that the growth of thecultured T-cells was entirely dependent upon an exogenous supply of IL2. Within 24 hours, sigmoid IL 2 dependent dose-responsive curves, whichwere amenable to probit analysis, yielded reproducible, quantitativedata, such that a comparison of IL 2 titers was possible. Thedevelopment of an IL 2 assay, which was rapid, simple and quantitative,prompted experiments to define its biochemical characteristics. As aresult, it is now clear that IL 2 provides the mitogenic stimulus afterlectin or antigen initiated T-cell activation. The addition of a lectinor antigen to mononuclear cells results in at least three responses:first, release of a soluble factor from monocytes/macrophages (IL 1);second, under the influence of this monokine, the release of Il 2 by aspecific T-cell subset; and third, expression of IL2 receptors andbinding to IL2 to its receptor in a proliferative response. While theseresponses all require initiation by lectins or antigens, theproliferative response is mediated solely by IL 2.

Interleukin 2 (IL 2, T-cell growth factor), discovered by Morgan et al.[Morgan, D. A., et al., (1976) Science 193:1007] is produced byT-lymphocytes after antigen-or mitogen-stimulation and is required forproliferation of activated T-cells. IL 2 is an essential mediator of theimmune response [Paetkau, V., (1981) Nature 294:689; Ruscetti, F. W., etal. (1981) Blood 47:379] and there is preliminary evidence that it mayalso be responsible for the abnormal cell proliferation in humanlymphoblastic leukemias [Gillis, S., et al. (1980) AACR, Abstract No.955, p. 238; Venuta, S., et al. (1983) Blood 61:781].

These observations have led investigators to initiate antigen-specificprliferative responses, followed by attempts to maintain functional,antigen-specific T-cells in continuous IL 2-dependent proliferationculture. The ability to culture functional monoclonal T-cells shouldprovide the cellular reagents necessary for detailed studies of thenature of the T-cell immune response. The cultured T-cells have alsoprovided the cellular reagents necessary for detailed studies of IL 2cellular interaction.

Results of experimentation indicate that IL 2 satisfies most of thecriteria for a hormone. It is produced by a distinct cell type and actsas a distance on other cell types by means of specific receptors. Studyof the molecular mechanisms of IL 2 production, hormone-receptorinteraction, and the identification of IL 2 agonists and antagonistsshould provide new insights into pathological disease states whichinvolve T-lymphocytes.

Studies of the mechanism of action of IL 2 using unpurified or partiallypurified preparations have been very difficult because conditioned mediacontain other lymphokines and cytokines with potent biologicalactivities. Several groups have reported purification procedures forboth murine [Watson, J., et al. (1979) J. Exp. Med. 150:849;Granelli-Piperno, A., et al. (1981) J. Exp. Med. 154:422] and human IL 2[Mier, J. W., et al. (1980) Proc. Nat'l. Acad. Sci. U.S.A. 77:6134;Gillis, S., et al. (1980) J. Immunol. 124:1954; Robb, R.J., et al.(1981) Mol. Immunol. 18:1087]. These IL 2 preparations have permitted anincreasingly better definition of IL 2 regulation.

The work of Granelli-Piperino et al. Supra involves mouse IL 2 which isnot active in humans and, differs in molecular weight and isoelectricpoint from human IL 2. It is noted that the method of preparation and/orpurification of mouse IL 2 differs from that of the present invention.Granelli et al. use preparative electrophoresis.

The work of Mier et al. [J. Immunology (1982) 128:1122] uses preparativegel electrophoresis so differs from the invention detailed herein. Nouse of Sendai virus or Daudi cells is found in Mier et al and thedisclosed molecular weight is 13,000. The Mier et al. reportedpurification factor is 800 fold as compared to the present work whichpurifies IL 2 over 37,000 fold. Also note the specific activity of IL 2is a fraction of that obtained in the invention. No work in humans isreported.

The work of Gillis et al. [(1980) J. Immunol. 124:1954 uses a simplemethod to prepared IL 2 containing fractions differing from theextensive preparative method of the invention. Also, the work isdependent on Daudi cell stimulation. No Sendai viral stimulation isused. The molecular weight of Gillis et al. is of the first impression.No work in humans is shown in Gillis et al. The majority of the Gilliset al. evidence for IL2 is . . . admittedly generated from murinesystems . . . " (p. 1960).

The work of the invention contains information from several papers whichare hereby incorporated by reference as follows:

(1) Ciobanu, Niculae et al. (1983) J. Clin. Immunol. 3:332.

(2) Mertelsmann, Roland et al. (1983) in Normal and NeoplasticHematopoiesis pp. 545-555 Alan R. Liss, New York

(3) Welte, Karl et al. (1982) J. Exp. Med., 156:454.

(4) Flomenberg, W., et al. (1983) J. Immunol. 130:2644.

(5) Merluzzi, Vincent et al. (1983) J. Immunol. 131:806.

(6) Venuta, S., et al. (1983) Blood 61:781.

(7) Welte, K., et al. (1984) Blood in press.

In the course of purification of the highly purified human IL 2 of theinvention, several reproducible conditions for the production of highlevels of human IL 2 have been previously developed. First, nylon-columnpurified peripheral blood lymphocytes prepared from many allogeneicdonors were cultured for 72 hours at 4×10⁶ cells/ml in the presence of1% phytohemagglutinin-M and a 0.25% bovine serum albumin. In general,phytohemagglutinin-stimulated leukocytes from a single donor producemuch lower levels of IL 2. Second is a method that relies on the use ofphytohemagglutinin-stimulated cells from a single donor butco-cultivated with x-irradiated cells from a B-lymphoblastoid cell linesuch s RM-1, SR, or Daudi. The rationale for use of B-cell lines was toprovide a standard source of allogeneic stimulation and thus eliminatethe need for mixing several allogeneic donors. Third, after screeningfor cell lines that will release IL 2 after mitogen stimulation, a humanT-leukemic cell line Jurkat was found to be a high producer. This cellline has since been used by many investigators as a consistent source ofIL 2. Tumor promoters have also been used as costimulators, leading tohigh IL 2 concentrations in the conditioned media, to high IL 2concentrations in the conditioned media, but these preparations wouldcertainly be difficult to use to humans because of the potentiallyincreased risk of cancer promotion.

In the past, IL 2 has been induced as crude lymphocyte-conditionedmedium by any of the three methods previously described and preparedunder serum-free conditions with bovine serum albumin (0.2%) as theserum replacement.

After ultrafiltration, the crude lymphocyte-conditioned medium wasconcentrated by (NH₄)₂ SO₄ fractionation and then dialyzed. The dialyzedactive sample was passed over an anion-exchange chromatographic column(diethylaminoethyl-Sepharose). IL 2 activity eluted as a broad peakcentered at approximately 0.07M NaCl. Subsequent gel filtration with anUltrogel AcA 54 column separated the IL 2 from most of the detectableproteins, and this sequence of steps achieved more than a 400-foldincrease in specific activity over the IL 2 in the serum-freelymphocyte-conditioned medium. The IL 2-containing material was furtherpurified using polyacrylamide gel electrophoresis containing sodiumdodecyl sulfate. The IL 2 activity corresponded to a pair of proteinbands present in the 13,000 molecular weight region in the sodiumdodecyl sulfate gel. This procedure has been reported by Mier et al.(1982) Supra and Frank et al., (1981) J. Immunol. 127:2361, for thepurification of human IL 2. More recently the use of phenylsepharose hasbeen introduced as a first step in the purification scheme of IL 2[Stadler et al., (1982) J. Immunol. 128:1620]. However, sincephenylsepharose as hydrophobic absorption chromatography was used onlyin the first step of purification, the major advantages of thistechnique for separation of multiple lymphokines were not utilized (seebelow).

Thus although reports are known of purification procedures for bothmurine and human IL 2, and these preparations have permitted anincreasingly better definition of IL 2 regulation, the purity of suchpreparations has not been well-documented.

We recently found that hydrophobic adsorption chromatography followingother separation means permits the purification of human IL 2 toapparent homogeneity. A 37,000-fold high purification may be achievedcompared to the 60-fold purification reported by Stadler et al. (1982)Supra and the 800-fold purification disclosed by Mier et al., (1982)Supra. Our purified IL 2 preparation is apparently free of all otherlymphokines and factors present in the crude lymphocyte-conditionedmedium, including Interferon (alpha and gamma), colony stimulatingfactor (CSF), B-cell growth factor (BCGF), serum thymic factor (FTS) andB cell inducing factor (BIF or T-cell replacing factor). The highlypurified IL 2 obtained by us appears to be free of any contaminatingproteins in sodium dodecyl sulfate-polyacrylamide gel electrophoresisafter staining with a silver nitrate method [Merril, C. R., et al.(1979) Proc. Nat'l. Acad. Sci. U.S.A. 76:4335), and after exolabellingwith I¹²⁵ [Branca, A. A. et al., (1981) Nature 294:768; Bio-Rad(Rockville Center, New York) Technical Bulletin 1071 Iodinating Proteinswith Enzymobeads (May 1981) which references are hereby incorporated byreference].

Up to three functionally active bands were detected in this preparation.Elution of the materials from the sliced gels possessed high specificactivity. We found that the molecular species of IL 2 are dependent onthe experimental conditions used for IL 2 induction. All purificationsteps have been developed to allow large scale production and arecurrently being used for 10 liters of conditions medium per week.

Although this purification protocol has been successfully used not onlyfor IL 2 from normal lymphocytes, but also for IL 2 from leukemiclymphoblasts as well as from the Jurkat cell line, our work has focusedpredominantly on IL 2 from normal human lymphocytes. Since the purematerial was intended for use in humans, leukemic cell sources as wellas induction conditions using tumor promoters [Frank et al., (1981) J.Immunol. 127:2361; Stradler et al., (1982) Supra. Stern, A., et al.(1984) Proc. Nat'l. Acad. Sci. 81:871 and European Patent Application EP 0089062 by Ajinomoto] and/or tumor cell line costimulators [Gillis etal., (1980), J. Immunol. 124:1954] appeared highly undesirable for thispurpose. Furthermore, there is the possibility tht the leukemic IL 2might be different from normal IL 2 which, although unlikely, could bean additional hazard for in vivo administration. Robb, R. J., et al.[Proc. Nat'l. Acad. Sci. U.S.A. (1983) 80:5990] at 5993 note such adifference since a structural feature of the IL 2 molecule recognized byspecific antibody is absent or masked on most IL2 secreted by normalhuman lymphocytes.

Obtaining highly purified human IL 2 according to the inventioncomprises conditioning the source medium to increase the IL 2 contentthereof; concentrating the proteinaceous components of the medium byprecipitating same and separating therefrom unprecipitatednon-proteinaceous material and smaller molecules (e.g., MW less than5,000), such as amino acids and small peptides; removing extra saltsfrom the proteinaceous material via dialysis; separating some of thenon-specific proteins from desired proteinaceous material by anionexchange; effecting separation by molecular weight of the IL2-containing proteinaceous material by gel filtration; and separating IL2, which is highly hydrophobic, from other lymphokines of about the samemolecular weight via hydrophobic chromtography. Further purification ofIL 2 is achieved using high pressure liquid chromatography to insureremoval of B-cell growth factor (BGF) and B cell inducing factor (BIF)also known as T-cell replacing factor, in those batches where thefactor(s) dose not completely separate out after hydrophobicchromatography. HPLC also removes trace impurities.

FIG. 1 relates to diethylaminoethyl cellulose (DE 52) chromatography ofIL 2. A dialyzed sample of the (NH₄)₂ SO₄ -precipitate fraction wasloaded on the DE 52 column. Proteins were eluted with a linear gradientof NaCl (0-0.3M) in 0.05M Tris-HCl (pH 7.8) and 5 ml fractions collected(absorbtion at 280 nm (filled circles), IL 2 (U/ml produced in thepresence (blank triangles) or absence (0--0) of Daudi cells).

FIG. 2 concerns gel filtration of IL 2 on AcA 44 Ultrogel. DE52-purified IL 2 was loaded on an AcA 44 Ultrogel column and eluted withphosphate-buffered saline (pH 7.2)/0.1% polyethyleneglycol (MW 6000).Six ml fractions were collected. The column was calibrated with bovineserum albumin (MW 68,000), chymotrypsinogen (MW 25,000), andribonuclease A (MW 14,000) (absorption at 280 nm (filled circles), IL 2(U/ml) produced in the presence (blank triangles) or absence (0--0) ofDaudi cells).

FIG. 3 illustrates chromatography of IL 2 on Blue Agarose. AcA 44Ultrogel-purified IL 2 was applied to a Blue Agarose column and elutedwith a linear gradient of phosphate-buffered NaCl (0.05-0.8M). Twenty mlfractions were collected (O.D. at 280 nm (filled circles), IL 2 (U/ml)(filled triangles), alpha-Interferon (U/ml) (0--0), NaCl molarity (M)(blank squares)).

FIG. 4 relates to chromatography of IL 2 on Procion®-Red Agarose. The IL2-containing fractions from Blue Agarose were pooled and loaded on aProcion®-Red Agarose column. The bound proteins were eluted with astepwise increases in salt concentration (0.15-1.0M NaCl in phosphatebuffer) (O.D. at 280 nm (filled circles), IL 2 (U/ml) (filledtriangles)).

FIG. 5 illustrates a sodium dodecyl sulfate-polyacrylamide gelelectrophoresis profile of various steps of IL 2 purifications ((a)molecular weight standards: phosphorylase b (MW 94,000), bovine serumalbumin (MW 68,000), ovalbumin (MW 43,000), carbonic anhydrase (MW30,000), soybean trypsin inhibitor (MW 20,000), andalpha-lacphocyte-conditioned medium; (c) dialyzed ammonium sulfateprecipitate; (d) pool of IL 2-containing diethylaminoethyl celluloseeluate; (e) IL 2-containing fractions pooled from AcA 44 Ultrogel gelfiltration).

FIG. 6 shows the sodium dodecyl sulfate-polyacrylamide gelelectrophoresis of Blue Agarose- and Procion®-Red Agarose-purified IL 2.IL 2 was treated with 2% sodium dodecyl sulfate and 5 mM2-mercaptoethanol and applied to a 5-20% gradient gel. The protein bandswere visualized by a silver nitrate method. The following markerproteins (200 ng each) were used: ovalbumin (MW 43,000), carbonicanhydrase (MW 30,000), soybean trypsin inhibitor (MW 20,000) andalpha-lactalbumin (MW 14,5000) ((a) protein standards; (b) BlueAgarose-purified IL 2 produced in the absence of Daudi cells; (c)Procion®-Red Agarose-purified IL 2 prepared in the absence of Daudicells; (d) Procion®-Red Agarose-purified IL 2 obtained by costimulationwith Daudi cells).

FIG. 7 shows the IL2 activity of 1 mm gel slices after sodium dodecylsulfate-polyacrylamide gel electrophoresis of Procion®-RedAgarose-purified IL 2 produced in the presence or absence of Daudicells. The IL 2 preparations were treated with 2% sodium dodecyl sulfateand 5 mM 2-mercaptoethanol and applied to a 15% polyacrylamide gel.After electrophoresis, the gel was sliced into 1 mm sections andproteins eluted with 0.3 ml phosphate-buffered saline (pH 7.2). Theeluted material was assayed for IL 2 activity. The arrows indicate theposition of the protein standards soybean trypsin inhibitor (MW 20,000)and alpha-lactalbumin (MW 14,500) (IL 2 (U/ml) produced in the presence(blank triangles) or absence (0--0) of Daudi cells).

FIG. 8 relates to the gel filtration chromatography of BlueAgarose-purified IL 2 on high performance liquid chromatography in thepresence and absence of sodium dodecyl sulfate and dithiothreitol. IL 2,native or treated with 1% sodium dodecyl sulfate and 10 mMdithiothreitol, was applied to a high performance liquid chromatographygel filtration column. The following protein standards were used: bovineserum albumin (MW 68,000), ovalbumin (MW 43,000), chymotrypsinogen (MW25,000), and ribinuclease a (MW 14,000). The arrows indicate theposition of chymotrypsinogen and the calculated 17,000 daltons molecularweight region. The dotted area identifies the position of native IL 2and the second peak corresponds to the sodium dodecyl sulfate-denaturedIL 2.

FIG. 9 concerns the isoelectrofocusing of AcA 44 Ultrogel-purified IL 2.An isoelectrocfocusing column (110 ml) was prepared by loading a 5-60%glycerol density gradient containing 2% Ampholines of pH 3.5-10. IL 2eluted from AcA 44 Ultrogel was supplemented with 2% Ampholines (pH3.5-10) and 20% glycerol and was layered onto the isodense region of thecolumn gradient. Constant power was then applied to the column with aterminal voltage of 2000 V and a current of 5 mA (24 hr, 4° C.) (IL 2(U/ml) in the presence (open triangles) or absence (0--0) of Daudicells, pH gradient (filled circles)).

FIGS. 10-12 follows thymidine uptake in patients with SCID, leukemiasand bone marrow transplants.

The examples below are meant to illustrate the invention withoutlimiting it.

Preparation of Lymphocyte-Conditioned Medium (Fraction I)

Human lymphocytes were obtained from peripheral blood of multiple donorsat New York Blood Center. In a typical procedure, the cells wereinitially stimulated by Sendai Virus (10⁴ U/ml) as part of a protocol toinduce Interferon. Twelve hours later the culture medium, rich inalpha-Interferon, was removed by centrifugation (800×g). The cells wereresuspended to 4×10⁶ /ml in serum-free RPMI 1640 (obtained from Gibco,Grand Island) supplemented with 0.25% bovine serum albumin (obtainedfrom Sigma, St. Louis, Mo.) and 1% phytohemagglutinin-M (obtained fromGibco) and incubated at 37° C. for 48 hours. In some preparationsirradiated (5000 rad) Daudi cells (10⁶ /ml) were added to the medium inorder to increase IL 2 production. At the end of the incubation, cellsand cell debris were separated from the conditioned medium bycentrifugation (10,000×g, 15 min) and the supernatant was used forpurification of IL 2.

Ammonium Sulfate Precipitation (Fraction II)

1683 gm (NH₄)₂ SO₄ were added to 3 liters of lymphocyte-conditionedmedium to achieve 80% saturation. After gentle stirring overnight at 4°C., the precipitate was spun down (10,000×g, 15 min), dissolved in 0.05MTris-HCl (pH 7.8) in a final volume of 300 ml, and subsequently dialyzedagainst 50 volumes of 0.05M Tris-HCl buffer (pH 7.8) for 48 hours withfive changes of the dialyzing buffer.

Anion Exchange Chromatography (Fraction III)

For analytical purposes, 10 ml of the dialyzed concentrate was loaded ona 40 ml column of microgranular diethylaminoethyl cellulose (DE 52,obtained from Whatman, England) which had been previously equilibratedwith 0.05M Tris-HCl (pH 7.8). The column was washed with 80 ml of thesame buffer and proteins, including IL 2, were eluted using a lineargradient of Tris-buffered NaCl (0-0.3M NaCl) and 5 ml fractions werecollected. IL 2-containing fractions were pooled and dialyzed againstphosphate-buffered saline (pH 7.2) containing polyehyleneglycol (MW6000) (50%, w/v) in order to concentrate pooled fractions. For largescale purification, 300 ml of diethylaminoethyl-cellulose slurry,equilibrated with 0.05M Tris-HCl (pH 7.8) was gently mixed with 300 mlof redissolved and dialyzed ammonium sulfate precipitate. After 30minutes the diethylaminoethyl cellulose was spun down and thesupernatant saved (Supernatant 1). The pellet was resuspended in 300 mlof 0.05M Tris-HCl (pH 7.8) containing 0.01M NaCl. After 10 minutes thediethylaminoethyl cellulose was spun down again (1,000×g) and theresulting supernatant pooled with Supernatant 1. The pooled supernatantswere concentrated by dialysis against polyethyleneglycol (MW6000)/phosphate-buffered saline (pH 7.2) as described above.

Gel Filtration (Fraction IV)

The concentrated diethylaminoethyl cellulose preparation was applied in10 ml aliquots to an AcA 44 Ultrogel (obtained from LKB, Rockland, Md.)column (2.5×90 cm), which had been previously equilibrated withphosphate-buffered saline (pH 7.2) containing 0.1% polyethyleneglycol(MW 6000). The flow rate was adjusted to 30 ml/hr and 6 ml fractionswere collected. IL 2-containing fractions were pooled. The column wascalibrated with bovine serum albumin (MW 68,000), chymotrypsinogen (MW25,000), and ribonuclease A (MW 14,000), all obtained from Pharmacia(Piscataway, N.J.). Subsequent to the preceding work, we have come toprefer the AcA 54 column over the AcA 44.

Chromatography on Blue Agarose (Fraction V)

Two hundred ml of the active fractions pooled from the AcA 44 Ultrogelcolumn were applied to a Blue Agarose column (obtained from BRL,Gaithersburg, Md.) with a bed volume of 40 ml that had been previouslyequilibrated with phosphate-buffered saline (pH 7.2). A linear gradientof NaCl (0-0.8M) in phosphate-buffered saline (pH 7.2) was applied and20 ml fractions were collected. The IL 2-containing fractions werepooled and polyethyleneglycol (MW 6000) added to a final concentrationof 0.1% (w/v) to stabilize the IL 2.

Chromatography on Procion^(R) -Red Agarose (Fraction VI)

The pool of active fractions eluted from Blue Agarose was dialyzedagainst phosphate-buffered saline (pH 7.2) and loaded on a 10 mlProcion^(R) -Red Agarose column (obtained from BRL), which had beenpreviously equilibrated with phosphate-buffered saline (pH 7.2). Thecolumn was then washed with phosphate-buffered saline (pH 7.2) and boundproteins were eluted by using a stepwise gradient of NaCl inphosphate-buffered saline (pH 7.2) with a starting salt concentration of0.3M NaCl and a final concentration of 1.0M NaCl.

High Performance Liquid Chromatography (for Trace Impurities)

BIF and IL-2 sometimes copurified with partially overlapping peaksthrough a number of steps: separation was achieved after the red agarosestep above. Sometimes this separation showed partial overlap of the twoactivities. This appears to be dependent on the batch of Ly-CM used. Afurther step using reverse phase HPLC could also be used to effectcomplete separation or removal of trace impurities. The high salteluates containing both IL-2 and BIF from red agarose were thenfractionated by reverse phase HPLC on a Protesil 300 column (Whatman)using increasing concentrations of propanol in TEAP (1% phosphoricacid-triethylamine, pH 3.0) or acetic acid-pyridine buffer pH 4.0. Forexample:

Reverse Phase High Performance Liquid Chromatography (RP-HPLC)

RP-HPLC was performed with a Waters HPLC system (Walters, Associates,Milford, MA). The HPLC system included two M6,000 solvent deliverypumps, a model 400 variable wavelength detector, a data module and adata processor. The separation was performed on a Protesil 300 column(Whatman). The buffers used were: Buffer A: 0.9M acetic acid/0.2Mpyridine, pH 4.0; buffer B: buffer A in 50% 1-propanol (Burdic andJackson, Lab., Muskegon, MI). Acetic acid and pyridine (HPLC grade) werepurchased from Fisher, Scientific Co.). The IL2 containing pool obtainedfrom Procion^(R) -Red Agarose chromatography was acidified with aceticacid to pH 4.0 and injected onto the Protesil 300 column without regardto sample volume. The column was washed with buffer A (20 min) and boundproteins were eluted using a steep gradient 0-40% buffer B within thefirst 20 min and a 40-100% gradient of buffer B in 120 min. The flowrate was adjusted to 1 ml/min and 3 ml fraction were collected. One-halfof each fraction was immediately stabilized by addition of 10micrograms/ml bovine serum albumin and dialysis against PBS. Protein wasestimated by Bio-Rad Protein Assay (microassay procedure using bovinealbumin as a standard). IL2 eluted at 45% propanol in TEAP.

High Performance Liquid Chromatography for Molecular WeightDetermination

A micromeritics liquid chromatography Model 700 B (Micromeritics,Norcross, Ga.) with a fixed wavelength detector and injector system wasused. The chromatography was performed either in the presence or absenceof sodium dodecyl sulfate/dithiothreitol. Under non-denaturingconditions, 1 ml of Blue Agarose-purified IL 2 was injected into aMicropak TSK 3000 SW column (from Varian, Sunnyvale, Calif.) and elutedwith 0.035M sodium phosphate buffer (pH 6.8) at a flow rate of 0.8ml/min. Fractions of 0.4 ml each were collected and 0.1%polyethyleneglycol (MW 6000) (w/v) was added to the fractions. Thecolumn was calibrated with bovine serum albumin (MW 68,000),chymotrypsinogen (MW 25,000), and ribonuclease A (MW 14,000), allobtained from Pharmacia. For analysis under denaturing conditions, 1 mlof Blue Agarose-purified IL 2 was treated with 1% sodium dodecyl sulfateand 10 mM dithiothreitol at 37° C. for 1 hour and loaded onto the samecolumn (previously equilibrated with 0.035M sodium phosphate buffer (pH6.8) containing 0.1% sodium dodecyl sulfate and 1 mM dithiothreitol).Marker proteins were pre-treated in the same way and then used forcolumn calibration.

Isoelectrofocusing

Ten mls of the AcA Ultrogel preparation of IL 2 were supplemented with20% glycerol (v/v) and 2% Ampholine (v/v) (pH 3.5-10) (from LKB). A5-60% glycerol density gradient, containing 0.1% polyethyleneglycol (MW6000) (w/v) and 2% Ampholine (pH 3.5-10) was layered into anisoelectrofocusing columm (110 ml from LKB). The IL 2 sample was appliedonto the isodense region of the gradient, followed by focusing for 24hours at 4° C. using a constant power supply (Model 2103 from KKB). Theterminal voltage was 2000 V and the terminal current 5 mA. Five mlfractions were collected and the pH determined in every fraction. Allfractions were dialyzed against phosphate-buffered saline (pH 7.2)containing 0.1% polyethyleneglycol (MW 6000) (w/v) to remove the bulk ofAmpholine and glycerol. The IL 2-containing fractions were pooled.

Concanavalin A-Agarose Chromatography

One ml of Procion^(R) -Red Agarose-purified IL 2 (500 U/ml) was loadedon a 2 ml concanavalin A (Con A) - agarose column (from Pharmacia)equilibrated with 0.02M sodium phosphate buffer (pH 7.2) containing 1MNaCl and 1 mM each of MgCl₂, MnCl₂, and CaCl₂. The column was washedwith the equilibration buffer and the proteins were eluted with the samebuffer containing 0.1M alpha-methyl-alpha-D-mannoside (obtained fromSigma).

Wheat Germ Agglutinin Column Chromatography

The wheat germ agglutinin column (2 ml from Pharmacia) was equilibratedwith phosphate-buffered saline (pH 7.2) and 1 ml of Procion^(R) -RedAgarose-purified IL 2 was loaded onto the column. After washing withphosphate-buffered saline (pH 7.2) the column was eluted withphosphate-buffered saline (pH 7.2) containing 0.1M N-acetyl-glucosamine(obtained from Sigma).

Treatment with Neuraminidase

Blue Agarose-purified IL 2 (1000 U/ml) was adjusted to pH 5.0 withacetic acid and added to agarose-bound neuraminidase (from Clostridiumperfringens, Type VI-A, supplied by Sigma). The mixture was incubatedfor 90 min at 37° C. with gentle shaking. The neuraminidase-agarose wasthen removed by centrifugation and the pH of the IL 2-containingsupernatant was adjusted to 7.8 with Tris base. A control sample wastreated in the same way except that the neuraminidase-agarose wasremoved prior to the incubation.

Protein Assay

The protein content of samples was measured using the Lowry technique[Lowry, O. H., et al. (1951) J. Biol. Chem. 193: 265]. For proteinconcentrations lower than 5 micrograms/ml, samples were subjected tosodium dodecyl sulfate-polyacrylamide gel electrophoresis; the proteinbands were visualized by the silver staining technique [Merril, C. R.,(1979) Supra]; and the protein concentration estimated by comparisonwith known amounts of protein standards (soybean trypsin inhibitor andalpha-lactalbumin). Serial dilutions (200 ng to 2 ng) of these markerproteins were used.

Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis

The discontinuous Tris-glycine system of Laemmli [Laemmli, U.K., (1970)227: 680] was used for 1.5-mm thick slab gels using a 5-20% gradient ora 15% of acrylamide. The samples were analyzed under both reduced (2%sodium dodecyl sulfate, 5% mercaptoethanol) and non-reduced (2% sodiumdodecy sulfate) conditions. After electrophoresis, gels were stainedwith Coomassie Brilliant Blue or by a silver nitrate method [Merril, C.R., et al., (1979) Supra]. Apparent molecular weights were determinedusing protein standards phosphorylase b (MW 94,000), bovine serumalbumin (MW 68,000), ovalbumin (MW 43,000), carbonic anhydrase (MW30,000), soybean trypsin inhibitor (MW 20,000) and alpha-lactalbumin (MW14,500). After electrophoresis, the gels were sliced into 1-mm sectionsand proteins from each slice were eluted in 0.3 ml phosphate-bufferedsaline (pH 7.2). After 12-18 hours, the eluted materials were assayedfor IL 2 activity.

Assay for IL 2 Activity

For the IL 2 assay, 4000 murine IL 2-dependent cytotoxic T-cell linecells were grown in the presence of log 2 dilutions of putative IL2-containing medium in 96-well microtiter plate (obtained from Costar,Cambridge, Mass.). The total volume in each well was 0.2 ml. Twenty-fourhours later, 0.5 microcurie of 3H-thymidine (specific activity 20Ci/mmole, supplied by New England Nuclear, Boston, Mass.) were added toeach well. After 4 hours, the cells were harvested on glass fiber stripsand 3H-thymidine incorporation measured in a liquid scintillationcounter (from Packard, Downers Grove, Ill.).

The IL 2 concentration in the experimental sample was then calculated byprobit analysis [Gillis, S., et al. (1978) J. Immunol. 120: 2027], usinga standard containing 2 U/ml of IL 2. One unit activity is equivalent tohalf-maximal stimulation of 6 day old PHA-stimulated lymphoblastsobtained from normal human donors.

High levels of IL 2 production were achieved by sequential stimulationof pooled peripheral blood lymphocytes from multiple donors. Peripheralblood lymphocytes were first stimulated by Sendai Virus for 12 hours.After a change of serum-free culture medium, these cells wererestimulated by phytohemagglutinin for an additional 48 hours.

Sendai Virus or phytohemagglutinin alone stimulated the production of IL2 at a 6-10 U/ml level, while sequential stimulation by Sendai Virus andphytohemagglutinin increased IL 2 production to 50-100 U/ml. Anadditional increase in IL 2 production, up to 200 U/ml, was achieved bycostimulation with Daudi cells.

Lymphocyte-conditioned medium was precipitated with (NH₄)₂ SO₄ at 80%saturation. This yielded an approximate 10-fold concentration of theproteins with high recovery of IL 2 activity. See Table I.

Factor Assays

BIF T cell-replacing factor activity was measured in a plaque-formingassay for immunoglobulin secretion (Ralph, P. J., et al. (1984) J.Immunol. 132: 1858 or Saiki et al. (1981) J. Immunol. 127: 1044).Interferon content was assesed on inhibition of the cytophathic effectof vesicular stomatis virus (Stewart, W. E. II (1980) The InterferonSystems. Springer-Verlag, Vienna and New York). Colony stimulatingfactor activity was determined on the ability to support growth ofmarrow granulocyte-macrophage colony-forming cells (Broxmeyer, H. E., etal. (1982) Blood 60: 595).

B cell growth factor was assayed by the ability to enhance proliferationof anti-IgM-stimulated, purified tonsillar B cells and Staphylococcusaureus-induced proliferation of purified B cells (Welte, K., et al.submitted for publication).

Analysis of trace Polypeptides with a silver stain (Merrill, et al.(1979) Supra)

This stain is highly sensitive; combining two dimensionalelectrophoresis and a silver stain.

Two-dimensional electrophoresis: This electrophoresis was carried outaccording to O'Farrell [(1975) J. Biol. Chem. 250: 4007], with 3/10Biolyte (Bio-Rad) in the first dimension and a 10% acrylamide uniformgel in the second dimension. Isoelectric focusing was at 500 V for 20hr; slab gels were run at 20 mA/gel.

Staining: to stain the gels with silver (2) they are fixed in 50%methanol/12% acetic acid for 30 min (gels can be stored overnight inthis solution). The gels tend to shrink in the 50% methanol solution. Toexpand them prior to staining, they are placed in 10% ethanol/5% aceticacid for 2 hr, followed by three washes with 10% ethanol (5 min each).The gels are then soaked in 4% (wt/vol) paraformaldehyde/1.43% (wt/vol)sodium cacodylate (adjusted to pH 7.3 with HCl) for 30 min., followed bythree 5-min washes with 10% ethanol. The gels are then agitated gentlyfor 30 min in a cupric nitrate/silver nitrate solution (made bydissolving 3.5 g of silver nitrate in 100 ml of water followed byaddition of 1.5 ml of 0.5% cupric nitrate solution and then thesimultaneous addition of 4 ml of pyridine and 8 ml of ethanol). We havefound it necessary to use reagent-grade absolute ethanol in this step.

Next the gels are placed in fresh diammine solution (made within 5 minof use) prepared by mixing together 30 ml of a 19.4% (wt/vol) silvernitrate solution and 22.2 ml of a solution of sodium and ammoniumhydroxide [stock solution contains 100 ml of 0.36% NaOH, 45 ml of freshconcentrated NH₄ OH and 55 ml of 20% (vol/vol) ethanol]. Diamminesolution remaining after the procedure must be discarded because anexplosive complex may form upon storage!. After the diammine rinse, thegels were washed for 1 min in a reducing solution containing 2.5 ml of10% formaldehyde (10 ml of commercial formaldehyde solution in 100 ml ofwater), 6 ml of 1% citric acid, and 100 ml of ethanol in one liter ofwater. This wash was repeated, again for 1 min, followed by severalrinses in a second reducer, containing 5 ml of 10% formaldehyde, 5 ml of1% citric acid, and 100 ml of ethanol in one liter of water. Theproteins may begin to appear as brown or black spots at any time in thereducing solutions. Staining can be stopped by washing the gel insuccessive changes of deionized water. Image formation in the diamminestep may occur if reaent-grade absolute ethanol and fresh stocksolutions are not used. Surface contamination can be minimized bywashing the glass slab plates thoroughly, immediately after eacchelectrophoresis run, and using well washed surgical glovres whenhandling the gels. The gels are fragile after staining and should bephotographed for a permanent record.

Gels that are overdeveloped may be lightened with a photographic reducersuch as the copper reducer of Smith [Walls, E. J., et al. (1976) inPhotographic Facts and Formulas, revised and enlarged by Carrol, J. S.ed. (Prentice Hall, Englewood Cliff, N.J. pp. 170-180]. A fresh mixtureof equal volume of two stock solutions ("A" and "B") are required.Solution A contains 37 g of cupric sulfate and 37 g of NaCl dissolved inliter of water with the addition of sufficient concentrated ammoniumhydroxide to dissolve any precipitate. A deep blue solution should beformed. Solution B contains 458 g of sodium thiosulfate in 1 liter ofwater. Usually a 3:1 dilution of water to fresh reducer is used tolighten gels. The reduction is stopped by washing the gel in water.

Stained gels may be kept in water. Gels that are to be dried for storageor autoradiography should be first soaked in 30% (wt/vol) sodiumthiosulfate for 15 min followed by four 15-min water rinses. The gelsshould then be soaked for 5 min in a preserving solution [methanol/H₂O/glycerol, 70:27:3 (vol/vol) [Mayer J. W., (1976) Anal. Biochem. 76:369], followed by drying on 3 MM filter paper (Whatman) at 50° C. underreduced pressure for 2 hr.

Autoradiography: Gels that were to be autoradiographed were dried asdescribed above and then placed in x-ray film cassette holders (KodakX-omatic, with regular intensifying screens). Exposure was at -70° C.with Kodak XR-2 x-ray film for appropriate timed intervals. Films weredeveloped at 25° C. for 5 min in developer (Kodak KLX developer)followed by a 5-min fix (Kodak X-omatic fixer).

Radioiodination of Proteins with Enzymobeads

Bio-Rad technical bulletin, Supra method as follows (as used in Branca,Supra):

1. Rehydrate the Enzymobead reagent wit 0.5 ml distilled water at least1 hour before use. Store at 4° C. (Rehydrate the Singel ReactionEnzymobeads with 50 microliter water).

2. Make up 1% Beta-D-Glucose in aqueous solution. (2% Alpha-D-Glucosecan be used; however, it must be allowed to mutarotate overnight to theBeta configuration).

3. Into a disposable test tube or the single reaction vial add:

0.2M phosphate buffer pH 7.2: 5 microliter

Protein sample (IL2): 10-25 microliter (10-100 microgram in a minimumvolume of an azide-free buffer*)

Enzymobead Reagent: 50 microliter

1.0 mCiNa¹²⁵ I: 5-25 microliter

1% Beta-D-Glucose: 25 microliter

All in 175 microliters.

4. Mix the reagents and allow iodination to proceed at room temperaturefor 15-25 minutes. The reaction can be quenched by either of twomethods. The first requires centrifugation to remove the EnzymobeadReagent from the reaction mixture, followed by immediate removal of thesupernatant for subsequent gel filtration. The second method used forIL2 utilizes direct application of the test tube mixture to a gelfiltration column.

In both cases, a Bio-Gel P-6 DG column is recommended for the separationof the unbound iodide from the labeled protein.

Dialyzed (NH₄)₂ SO₄ precipitate was placed on a diethylaminoethylcellulose column (DE 52). IL 2 was eluted with a salt gradient from0-0.3M NaCl in 0.05M Tris-HCl (pH 7.8) buffer. The IL 2 produced in theabsence of Daudi cells eluted as broad peak at low salt concentration(0-0.03M NaCl), while the IL 2 produced by costimulation with Daudicells eluted at salt concentrations between 0.03 and 0.08M NaCl. seeFIG. 1. Under both conditions, the bulk of proteins were eluted athigher salt concentrations (0.01-0.3M NaCl). This permitted a separationof IL 2 from the bulk of proteins in large scale batch preparations byusing the 0.1M NaCl wash of the diethylaminoethyl cellulose for elutionof IL 2.

Anionic exchange chromatography on diethylaminoethyl cellulose achievedabout 50-fold purification and approximately 75% of the loaded IL 2activity may be recovered in this procedure. See Table I.

The material eluted from diethylaminoethyl cellulose may then beconcentrated approximately 20-fold by dialysis against 50%polyethyleneglycol (MW 6000) (w/v) and loaded onto an AcA 44 Ultrogelcolumn. The IL 2 produced in the absence of Daudi cells was eluted infractions 42-52 as a single peak corresponding to a molecular weight of26,000±4000 daltons. When IL 2 was produced by costimulation with Daudicells, a major peak of activity was eluted on fractions 52-66,corresponding to a molecular weight of 13,000-18,000 daltons, while aminor peak of activity was found at 26,000 daltons. See FIG. 2. The IL 2activity-containing fractions were pooled.

This purification step achieved about a 2.7-fold increase in thespecific activity and approximately 80% recovery of the loaded IL 2activity. See Table I. This step also effectively removed proteinshaving molecular weights greater than 30,000 daltons. See FIG. 5.

IL 2 bound strongly to Blue Agarose, while mostproteins did not bind tothe column, as shown in FIG. 3. IL 2 was eluted from this column with0.5-0.6M NaCl and could be clearly separated from alpha-Interferon,which eluted at 0.05-0.4M NaCl in phosphate buffer. See FIG. 3. In thispurification step the specific activity increased 25-fold, with 61%recovery of the loaded IL 2 activity. See Table I.

Procion^(R) -Red Agarose has different binding properties from that ofBlue Agarose [Thompson, S. T., et al. (1976), Proc. Nat'l. Acad. Sci.U.S.A. 73: 361; Watson, D. H., et al. (1978) Biochem. J. 173: 591].

IL 2 was also bound strongly to this column and eluted as a broad peakbetween 0.6-0.9M NaCl in phosphate buffer with peak activity in the0.7-0.8M NaCl eluate. See FIG. 4. This broad elution profile wassuggestive of molecular heterogeneity of IL 2. A majority of the otherproteins did not bind to Procion^(R) -Red Agarose, and the rest elutedat low salt concentrations, as shown in FIG. 4. The 0.7M-0.8M NaCleluate pool was found, through silver staining of a 5-20% gradient gel(sodium dodecyl sulfate-polyacrylamide gel electrophoresis), to containthree molecular components with molecular weights of 14,500±2000,16,000+1000 and 17,000±1000 daltons depending on the experimentalcondition used for the production of IL 2. See FIG. 7.

The protein content of the preparation was measured by comparing thedensity of protein bands, visualized by silver staining, with serialdilutions of protein standards of known concentrations. Taking intoaccount the limitation of this measurement, a specific activity ofapproximately 10⁶ ±10% U/mg protein and a final purification of 37,191-fold were calculated. The overall recovery of IL 2 was 19% afterProcion^(R) -Red Agarose chromatography (Fraction VI, Table I).

The strong binding of IL 2 to Procion^(R) -Red Agarose also made thisstep very useful for concentrating IL 2 from diluted preparations usinga two-steep elution method with phosphate buffer containing 0.5M and1.0M NaCl. Under this condition, IL 2 activity was fully recovered inthe 1.0M NaCl eluate.

The IL 2 preparation from various steps of purification were subjectedto sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis.Preparations obtained prior to the Blue Agarose chromatography(Fractions I-IV) were analyzed on a 5-20% gradient gel followed byCoomassie brilliant blue staining as shown in FIG. 5. Preparationsobtained after Blue Agarose chromatography and Procion^(R) -Red Agarosechromatography were also analyzed on a 5-20% gradient gel followed bythe highly sensitive silver staining method as shown in FIG. 6.

When IL 2 was produced in the absence of Daudi cells and denatured, theProcion^(R) -Red Agarose preparation showed only two active bands withMW of 16,000 and 17,000 daltons (FIG. 6(c)) under both reducing andnon-reducing conditions. When Daudi cells were used as costimulator forIL 2 production, one active protein band with a MW of 14,500 daltons wasobserved (FIG. 6(d)). If suboptimal concentrations of Daudi cells (lessthan 5×10⁵ /ml) were used, three protein bands with MW 14,500, 16,000and 17,000 daltons were found.

To obtain a better resolution, the purified IL 2 was also analyzed on a15% acrylamide gel. After staining, a molecular weight pattern similarto that obtained int he gradient gel was found. A parallel gel wassliced into 1-mm sections and proteins from each slice were eluted inphosphate-buffered saline (pH 7.2). Il 2 activity was found to belocalized in slice numbers corresponding to molecular weights of 14,000,16,000 and 17,000 daltons (FIG. 7). Re-electrophoresis of the proteinspresent in all three slices with IL 2 activity showed one single bandwith molecular weight identical to that of the eluted band.

Blue Agarose-purified IL 2, produced in the absence of Daudi cells, wasincubated with 1% sodium dodecyl sulfate and 20 mM dithiothreitol at 37°C. for 1 hour and applied to an high performance liquid chromatographygel filtration column. The column was eluted with buffer containing 0.1%sodium dodecyl sulfate and 1 mM dithiothreitol. As shown in FIG. 8,sodium dodecyl sulfate denatured IL 2 was eluted in the 17,000 daltonsmolecular weight region. Native IL 2, eluted with sodium dodecylsulfate-free buffer, exhibited an apparent molecular weight of 26,000daltons.

The IL 2 preparation obtained from the AcA 44 Ultrogel column wassubjected to isoelectrofocusing analysis using Ampholines with a broadpH range (pH 3.5-10). The IL 2 obtained without Daudi costimulation wasfocused with an approximate isoelectric point of 6.7. See FIG. 9. Thesame pI was found if peripheral blood lymphocytes were stimulated in thepresence of Daudi cells. The relatively broad foscusing range observed,pH 6.5-7.5, was probably due to the reported molecular heterogeneity ofIL 2 [Robb, R. J., et al., (1981) Supra]. The yield of IL 2 from theisoelectrofocusing column was approximately 30%. This method was,therefore, useful only for the biochemical characterization of IL 2, andnot advantageous for preparative purification.

We were unable to detect any binding of IL 2 to either agarose-boundconcanavalin A or to a wheat germ agglutinin column. Neuraminidasetreatment of IL 2 did not affect its biological activity of itsmolecular weight pattern.

The mitogenicity on normal peripheral blood lymphocytes, the capacity tosupport the growth of murine and human cytotoxic T-cell line and thepresence of other cytokines were studied in the highly purified IL 2. Inorder to test for the presence of phytohemagglutinin, the mitogenicityof the IL 2 preparations was studied on normal peripheral bloodlymphocytes. A low level of mitogenic activity, about 5% of that presentin lymphocyte-conditioned medium, was detected only in undiluted IL 2preparations obtained from the diethylaminoethyl cellulose purificationstep. Blue Agarose- and Procion®-Red Agarose-purified IL 2 wascompletely free of mitogenic activity. IL 2 obtained from Blue Agaroseand Procion®-Red Agarose chromatography reportedly very activelysupports the long term growth of human and murine cytotoxic T-celllines. Human cytotoxic T-cell line appear to require approximately 10U/ml purified IL 2 for their optimum growth, while murine cytotoxicT-cell lines. Human cytotoxic T-cell line appear to requiredapproximately 10 U/ml purified IL 2 for their optimum growth, whilemurine cytotoxic T-cell line are maximally stimulated at 2 U/ml.Procion®-Red Agarose preparations of IL 2 contained generally nodetectable pyrogen activity, alpha- or gamma-Interferon,granulocyte-macrophage colony-stimulating activity, T-cell replacingfactor, or thymocyte differentiating activity. (See above). Dr.Geneviene Incefy of Sloan-Kettering performed these thymocytedifferentiating factor assays.

Lymphocyte-conditioned medium harvested after sequential stimulation ofperipheral blood lymphocytes with Sendai Virus and phytohemagglutinin,and costimulation with Daudi cells, showed an IL 2 concentration of200--200 U/ml. It was possible, therefore, to obtain a high IL 2concentration in the absence of other potentially toxic costimulatorssuch as PMA [Robb, R. J., et al., (1981) J. Exp. Med. 154: 1455; Mizel,S. G., et al., (1981) J. Immunol. 126: 834], which could interfere withbiological testing and clinical trials of purified IL 2.

The purification procedure disclosed introduces the chromatography onBlue Agarose, on Procion®-Red Agarose and on HPLC as three newpurification steps for IL 2. Although it has been suggested that theseblue and red agarose dyes bind specifically to proteins containing thedinucleotide fold [Thompson, S. T., et al. (1976) Supra], we have foundno evidence for any effect of NAD+ or NADH on biological activity orbiochemical behavior of IL 2. The binding of IL 2 to these dyes may bedue to the electrostatic or hydrophobic interactions. The use of thesetwo steps permitted a 37,000-fold purification of IL 2 from mediumconditioned in the presence of 0.25% bovine serum albumin, with a 19%overall recovery of IL 2 activity. All other purification methods, forboth murine and human IL 2, have achieved neither a specific activitynor a yield comparable to those described here. (See discussion of workof Mier et al, Gillis et al. and Granelli-Piperno et al. Supra above).Also see German patent application No. 314 9360 by Sonnenborn, Hans H.,et al. where IL-2 prepared for production of mAb appears to becontaminated with gamma-interferon, albumin and pyrogen. Limited use ofhydrophobic chromatography (blue only) leads to an impure IL2 certainlynot pure enough for clinical use. In the work there is no analyticalpurity check and the goal of the work seems to be to produce antibody toan impure IL2, separated from PHA.

Our purification procedure also avoided time consuming steps. This hadmade our procedure very useful for large scale purification of IL 2.

Lymphokines and other regulator molecules such as IL 1, [Mizel, S. G.,et al. (1981) Supra], alpha- or gamma-Interferon, T-cell replacingfactor, and CSF [Burgess, A. W., et al. (1980) Blood 56: 947], havedifferent capabilities of forming hydrophobic interactions. Theseproperties were utilized to separate IL 2 from other lymphokines andfactors which contaminate most partially purified IL 2 preparations. Forexample, alpha-Interferon co-purified with IL 2 during ion exchangechromatography and gel filtration steps, but was clearly separated fromIL 2 by Blue Agarose chromatography. See FIG. 3. After chromatography onProcion®-Red Agarose, the IL 2 preparation did not contain anydetectable Interferon (alpha and gamma), granulocyte-macrophagecolony-stimulating factor, T-cell replacing factor, or thymocytedifferentiating activities.

                  TABLE II                                                        ______________________________________                                        Independence of BIF Action From IL-2                                                       Induced ISC                                                      ______________________________________                                        No addition + IL-2                                                                           0        BIF      BIF (1:8)                                                   0        868 ± 42                                                                            207 ± 22                                                 0        830 ± 16                                                                            219 ± 13                                  ______________________________________                                         ISC were induced in Sacstimulated B cells by Fraction V BIF (see table        III) (blue agarose purification, 0.8 M NaCl, containing less than 5U/ml       IL2, or a 1:8 dilution. Parallel incubations included 20% Fraction VI IL2     (see table I) (red agarose puri fication step, 100 U/ml). The number of       ISC in Bcell cultures with Sac alone, 38 ± 2, was subtracted. hp IL2       was free of BIF activity and did not enhance optimal or suboptimal            concentrations of BIF.                                                   

In addition, the Procion®-Red Agarose-purified IL 2 appeared to be freeof any contaminating proteins (FIG. 6).

Native IL 2 has been previously shown to exist in several molecularforms [Mier, J. W., et al., (1980) Proc. Nat'l. Acad. Sci. U.S.A. 77:6134; Gillis, S., et al., (1980) J. Immunol. 124: 1954; Robb, R. J., etal., (1981) Mol. Immunol. 18: 1087]. Here we show that the methods usedfor IL 2 induction by peripheral blood lymphocytes can be responsiblefor the heterogeneity. Native IL 2 produced in the presence of absenceof Daudi cells exhibited molecular weights of about 14,500 and 26,000daltons, respectively (FIGS. 2 and 8). Both molecular forms could beobtained by varying the concentration of costimulator cells. Theseresults demonstrated that molecular weight differences [reported byMier, J. W., et al. (1980) Supra and Gillis et al. (1980) J. Immunol.124: 1954] were most likely due to different methods of IL 2 induction.

Taniguchi et al. (1983) [Nature 302: 305 (1983)] report a cDNA codingfor a protein product with some characteristics of human IL 2. The humanmRNA used originated from a human leukemic cell-line stimulated byconcanavalin A. The DNA clone contains bacterial DNA as well to form thecDNA and the cDNA is expressed in an SV40 transformed monkey kidney cellline COS-7. It is questionable whether this represents a properlyglycosylated human IL 2. The deduced amino acid sequence has noN-glycosylation site. Low IL 2 activity is found (70 units per ml COScell medium). Extra amino acids also appear to be present in thestructure. No human studies were done with this material, nor largescale production.

After denaturation by sodium dodecyl sulfate, the 26,000-dalton IL 2 ofthe invention exhibited a molecular weight of 16,000-18,000 daltons byhigh performance liquid chromatography gel filtration. Sodium dodecylsulfate-polyacrylamide gel electrophoresis of this denatured formdemonstrated the presence of two biologically active bands withmolecular weights of about 16,000 and 17,000 daltons, respectively.These results, together with those of Caplan et al. [(1981)] J. Immunol.126: 1264], indicate that, after sodium dodecyl sulfate denaturation,human and murine IL 2 exhibit similar molecular weights. The molecularweight of human IL 2 produced in the presence of Daudi cells was notaffected by sodium dodecyl sulfate denaturation. Since native rat IL 2has been reported to show a molecular weight of 15,000 daltons [Gillis,S., et al. (1980) J. Immunol. 124: 1954; Smith, K. A., (1980)Immunological Rev. 51: 337; Smith, K. A., et al. (1980) MolecularImmunol. 17: 57], it appears that IL 2 activity is present in apolypeptide of about 14,500-17,000 daltons in all species studied. It isnot known if these different molecular forms have different functions,such as preferential stimulation of T cell subsets. It is also not knownwhether the same T-cell will switch its IL 2 synthesis from 26,000daltons to 14,500 daltons upon costimulation by Daudi cells, or whetherdifferent T-cell subsets are indeed responsible for the release of IL 2in two molecular forms.

Assuming two functional T-cell subsets, one subset would produce the26,000 MW IL 2 in response to phytohemagglutinin alone, while the secondsubset would require phytohemagglutinin as primary stimulus andcostimulation by Daudi cells as a second signal for the production of14,500 MW IL 2. Daudi cells express HLA-DR antigens and Fc receptors.Both of these surface molecules have been implicated in the augmentionof the IL 2 response [Palacios, R., et al., (1981) Cellular Immunol. 63:143; Shimizu, S., et al., (1982) J. Immunol. 128: 296]. The effect ofDaudi cells on the IL 2 response, however, does appear to be morecomplicated than previously suggested [Palacios, R., et al., (1981)Supra; Shimizu, S., et al., (1982) Supra], in view of: (a) the shift inmolecular weight of IL 2 from 26,000 to 14,500 daltons induced by Daudicells; (b) the augmentation of IL 1-independent IL 2 production as seenin the human lymphoblastic cell line Jurkat [Venuta, S., et al. (1983)Blood 61: 781]; while Friedman et al. [(1982) J. Immunol. 128: 935]recently reported that cells obtained from a patient with T-cell chroniclymphocytic leukemia, stimulated under identical conditions, releasedthe 14,500 MW form of IL 2.

The reason for the molecular heterogeneity of the sodium dodecylsulfate-denatured and native IL 2 remains to be explored. A variabledegree of glycosylation may provide an explanation of this phenomenon[Robb, R. J., et al., (1981) Mol. Immunol. 18: 1087; Clark-Lewis, I., etal., (1982) J. Immunol. 128: 180]. Robb et al. (1981) Supra have shownthat neuraminidase, glycosydases and inhibitors of glycosilation canreduce the heterogeneity of IL 2 produced by tonsil lymphocytes.However, we were not able to affect the molecular weight of IL 2 byneuraminidase treatment, nor were we able to detect any binding of IL 2to immobilized lectins (concanavalin A and wheat germ agglutinin). Thelack of binding of IL 2 to lectins has been previously reported by Mieret al. [Mier, J. W., et al., (1980) Supra]. The difference between theseresults are probably due to the different methods of induction andpurification of IL 2, which appear to affect the biochemicalcharacteristics of IL 2.

The purification steps described herein produced hp IL 2 with a specificactivity of about 10⁶ U/mg protein. Since the lowest molecular weight ofan active IL 2 polypeptide was 14,500 daltons, it could be calculatedthat 1 U/ml of IL 2 was equivalent to a molar concentration of 7×10⁻¹¹M. An IL 2 concentration of 1.4×10⁻¹¹ M or approximately 4×10⁵molecules/cell was required for half maximum stimulation of murinecytotoxic lymphocytes. Similar values have been reported by Mizel et al.for IL 1 [Mizel, S. G., et (1981) Supra].

The highly purified (hp IL 2) IL 2 may be used to investigate thebiological effects of IL 2, both in vitro and in vivo. In preliminaryexperiments, we have been able to partially restore, in vitro, theresponse of T cells of a patient with Nezeloff's syndrome in both theallogeneic mixed lymphocyte reaction (MLR) and in cell-mediatedlympholysis (CML) by addition of human Procion®-Red Agarose-purified IL2 (Fraction VI). These studies should contribute to the understanding ofnormal human lymphocyte function, immunoficiency syndromes, and thepathophysiology of human lymphoblastic leukemias (Gillis, S., et al.,(1980) AACR Abstract No. 955, p. 238; Venuta, S., et al., (1983) Supra.

hp IL 2 is useful in a variety of in vitro systems, including thecontinuous growth of antigen specific cytotoxic T-cells and theestablishment of IL 2 dependent long-term cell lines from patients withcertain T-cell neoplasias. It is also feasible to grow autologoustumor-specific human T-cells in large quantities in vitro and thentransfuse these cells in vivo with a therapeutic result. Further uses tobe considered are the establishment of long-term cultures of normalT-cells for drug testing and carcinogenicity tests.

Animal models that have been used to explore therapeutic uses of crudeconditioned media containing IL 2 are the nude mouse (T-cellimmunodeficiency) and the mouse immunosuppressed by cytoxan. Preliminaryresults suggest that the immune response can be normalized by thesemedia [Lipsick et al., (1981) Proc. Nat'l. Acad. Sci. 78: 2398; Merluzziet al., (1981) Cancer Res. 41: 850]. Preliminary studies using our ownmaterial suggest that the active ingredient in fact is IL 2.

Further studies in both mice [Miller et al., (1981) Eur. J. Immunol. 11:751] and men [Gillis et al., (1981) J. Clin. Invest. 67: 937] have shownthat aging and its associated immune defects might be related to adefect in IL 2 production.

Frabricus et al. U.S. Pat. No. 4,390,623 issued June 28, 1983 aremitogen-free and serum free crude IL 2-containing material which is notfurther purified and study its effect on cells in culture. No patientsare treated. The material is not pyrogen-free and Fabricus et al.propose to treat humans with IL 2 derived from cattle and/or pigs aswell.

More recently, Lopez-Botet et al., [(1982) J. Immunol. 128: 679],evaluated patients with severe combined immunodeficiency,Wiskott-Aldrich Syndrome, immunodeficiencies with hyper IgM, x-linkedagammaglobulinemia, and common variable immunodeficiency forproliferative response to phytohemagglutinin with and without additionof mitrogen-free supernatants containing IL 2. The hyporesponse tophytohemagglutinin in this group of patients was associated with adefect in the production of IL 2.

We have found that the defect of the proliferative response of T-cellsin patients with Nezeloff Syndrome, in immunodeficiency associated with(a) advanced age, (b) burn patients, (c) newborns, (d) Kaposi's Syndromein Homosexuals, (e) Hodgkin's disease, and (f) chemotherapy can almostbe completely normalized in vitro by additions of homogeneous hp IL 2.

Based on these encouraging results we show results herein of a combinedphase I and phase II trial of IL 2 in patients with congenital andacquired immunodeficiency syndrome. So far no untoward reactions havebeen seen in fifteen patients. (maximum dose levels reached 20,000 U/m²/day).

We anticipate extensive clinical trials and therapeutic potential forpatients with congenital immunodeficiency syndromes, Hodgkin's disease(T-cell defect frequent), Kaposi's Syndrome, immunosuppressionassociated with cancer, and immunosuppression associated withchemotherapy and/or radiation therapy; and for aged individuals as wellas patients with other immunodeficient states like patients after bonetransplantation therapy.

We believe that hp IL 2 alone or in combination with other lymphokinesmight become the treatment of choice for several of the above listedsyndromes, in a similar fashion as parenteral insulin has become thespecific therapy for diabetes mellitus.

Further use is anticipated in IL 2-dependent neoplasia such as ALL andneoplasias of mature T-cells. Modification of the hp IL 2 moleculeeither chemically or through addition of cytotoxic subtances to the IL 2molecule may allow selective elimination of IL 2-dependent neoplasticcells through blockage of receptor sites or cell type specific deliveryof toxic substances to IL 2 responder cells. This approach might also behelpful in selectively eliminating IL 2 responder cells in cases withover-reactive immunity, such as in autoimmune disorders.

The examples serve only to illustrate the therapeutic utility of thishighly purified IL 2 without limiting it to the specific examples shown.These examples are based on work which resulted in several papers whichare hereby incorporated by reference: Flomenburg, N., et al. (1983) J.Immunol. 130: 2644; Mertelsmann, Roland et al. in Normal and NeoplasticHematopoiesis pp. 545-555 (1983), Alan R. Liss Incorp., Ciobanu, Niculaeet al. (1983) J. Clin. Immunol. 3: 332 and Merluzzi, Vincent J. (1983)J. Immunol. 131: 806. Welte, K., et al. (1984) Blood in press.

The highly purified IL 2 (hp IL 2) of the invention has recently beenapproved by the Food and Drug Administration (FDA) for use as a drug;this IL 2 has IND number BB IND 1916.

Immunological Effects of IL2 in Primary Immunodeficiency Diseases

Five children with primary deficiencies of T cell function were studiedto assess the effects of highly purified exogenous Interluekin 2 (hp IL2) on their in vitro T cell responses. The lymphocytes from one childwith Nezeolof's T cell deficiency demonstrated absence of endogeneous IL2 production and improved proliferative responses to mitogen oralloantigen in the presence of exogenous hp IL 2. Moreover, during invitro mixed lymphocyte culture in the presence of exogenous hp IL 2, hislymphocytes were able to develop into cytotoxic effector cells. A secondchild with Nezelof's syndrome demonstrated a different type of defect.The lymphocytes from this child had less impairment of endogenous IL 2production. Although hp IL 2 increased the proliferation of his cells inresponse to PHA, similar augmentation was not seen after stimulationwith OKT3 or alloantigen. In cell-mediated cytotoxicity assays, aftermixed lymphocyte culture, natural killer-like activity was stronglyboosted in the cultures that contained IL 2, but T cell-mediatedcytotoxicity was not. The lymphocytes from three patients with severecombined immunodeficiency did not show improved proliferative responsesin the presence of hp IL 2. Thus, only one of the five patientsdemonstrated the combination of defective endogenous IL 2 production,but preservation of the ability to respond appropriately to exogenous hpIL 2. This child may therefore have suffered from a T cell defectpathophysiologically similar to that seen in nude or aged mice.

We have studied five children with defective T cell function caused byprimary immunodeficiency diseases in order to ascertain whether somehuman immunodeficiency states might be caused by defects in theproduction of or response to IL 2. One child subsequently received an invivo trial of hp IL 2. The results of these studies are presented andtheir implications discussed. Highly purified human IL 2 above was usedfor all in vitro work IL 2 assay was done as above.

Cell collection: All in vitro assays employed PBL collected from densitygradient centrifugation of a 1:1 mixture of peripheral blood and RPMI1640 on Ficoll-Hypaque (Lymphoprep, Accurate Chemical and ScientificCorp, Hicksville, NY). Cells suspended over the Ficoll-Hypaque layerwere harvested, washed three times in RPMI 1640, and then used forappropriate studies [Boyum, A. (1968) J. Clin. Lab. Invest. 91: 21S].E-rosette assays and immunofluorescent characterization were performedaccording to standard techniques [Kaplan, M. E., et al. (1974), J.Immunol. Methods 5: 131; Harzenberg, L. A., et al. (1978) in Handbook ofExperimental Immunology ed. by D. M. Weiss Blackwell ScientificPublications, Oxford, p. 22.1.).

T cell response to mitogens and microassay for IL production: PBL werediluted to a concentration of 2×10⁶ cells/ml in RPMI 1640+5% fetal calfserum (FCS). One hundred microliters of cells were mixed with equalvolumes of RPMI-5% FCS containing appropriate concentrations of mitogensand/or IL 2. The final concentrations used for the mitogens were 0.5%for phytohemagglutinin and 1 ng/ml for the monoclonal antibody OKT3[Chang, T. W., et al., (1981) Proc. Nat'l. Acad. Sci. U.S.A. 78: 1805)(Ortho Pharmaceuticals, Raritan, NJ]. IL 2 was used at 10 U/ml.

For each time point to be studied, duplicate plates were prepared. 0.5micro Ci of [³ H]TdR (specific activity 20 Ci/mM, New England Nuclear)was added to each well of the first plate. After an additional 4-hrincubation, cells were harvested on glass fiber strips and counted in aliquid scintillation counter. The second plate was spun to ensurepelleting of the PBL. The supernatants were removed and assayed for IL 2activity as described above. As previously described [Welte, K., et al.(1982), J. Exp. Med. 156: 454]. IL 2 production was maximal 24 hr afterinitiation of culture. Normal controls consisted of healthy volunteersranging from 4 wk to 40 yr in age.

Mixed lymphocyte culture (MLC): In vitro MLC was performed with the useof PBL. Fifty thousand responder cells were mixed with 50,000 stimulatorcells, which had been treated with 4000 rads (444 rad/min for 9 min in aCesium Gammacell 1000 irradiator (Atomic Energy of Canada Ltd.,Ottawa)). The cultures were performed in RPMI 1640 and 15% pooled humanserum (HS) supplemented with penicillin 100 U/ml, streptomycin 100micrograms/ml and glutamine 2 mM. A total volume of 150 microliter perwell was cultured in round bottom microtiter plates (NUNC, VanguardInternational, Neptune, NJ) at 37° C. in a humidified 5% CO₂ atmosphere.After 120 hr, plates were labeled with [³ H]TdR 1 microCi/well (6.7Ci/mmol, New England Nuclear). Eighteen hours later, they were harvestedwith the use of a Skatron multi-sample harvester (Flow Laboratories,Hamden, CT). After drying the filter papers, each sample was placed in ascintillation vial with 2 ml of scintillation fluid, cooled, darkadapted, and counted in a liquid scintillation counter. To assess theeffect of hp IL 2 on MLC, parallel cultured were tested with and withouthp IL 2. hp IL 2 was added to produce a final concentrtion of 20 U/ml[Dupont, B., et al. (1976), Adv. Immunol. 23: 107].

Cell-mediated lympholysis (CML) and natural killer cell (NK) assays:Effector cells for CML were developed by incubating equal numbers ofresponder PBL and 4000 rads irradiated stimulator PBL at a finalconcentrations of 1×10⁶ cells/ml in RPMI-10% HS in 25 cm² tissue cultureflasks (Corning, Medfield, MA) as previously described [Schendel, D. J.,et al. (1979) Tissue Antigens 13: 112]. After 6 days, the cells wereharvested and resuspended in fresh media (RPMI 1640-10% HS) atappropriate cocentrations dependent on the effector to target cellratios (E:T) to be used. Duplicate cultures with and without hp IL 2were prepared. hp IL 2 was added to produce a final concentration of 20U/ml.

Target cells for CML consisted of PHA-stimulated lymphoblasts that hadbeen cultured for 3 days in medium containing PHA at a 1:100 dilution ofthe stock solution. Targets were incubated for 1 hr with 250 micro Ci of⁵¹ Cr(Na₂ ⁵¹ CrO₄) specific activity 200 to 500 mCi/mg Cr, New EnglandNuclear), washed twice, and resuspended at a concentration of 30,000cells/ml. One hundred microliters of effectors and targets were mixed inround bottom microliter wells (Linbro, Flow Laboratories). Triplicatedeterminations were performed. Microtiter plates were spun momentarilyto ensure adequate mixing and incubated for 4 hr.

Supernatants were harvested with a Titertek Harvesting System (FlowLaboratories) and counted in a gamma counter for 1 min. Percentcytotoxicity is determined by the formula: ##EQU1##

Spontaneous release is defined as the number of counts produced byincubation of 3000 target cells in media without effectors. Maximumrelease wis the number of counts produced when 3000 target cells arelysed using 10% Triton X detergent (New England Nuclear).

The NK cell activity studied in the patients included both spontaneousNK activity of freshly isolated PBL as well as the NK activity which isdeveloped during 6 day in vitro MLC. It is defined as NK activitythrough the use of the normal NK target cell line. K562. The assays wereperformed in identical fashion as for the CML assay except that the K562cell lines was used as the target [West, W. H., et al. (1977) J.Immunol. 118: 355].

Case Summary--J.V.

J.V. was a 31/2-yr-old patient with Nezelof's syndrome. He came tomedical attention at the age of 2 because of a series of infectionssecondary to Gram-positive and Gram-negative bacteria, amebae, andfungi. Evaluation revealed low normal levels of immunoglobulin (IgG 810mg/100 ml, IgA 210 mg/100 ml, IgM 85 mg/100 ml). Complement levels werenormal. T cells were markedly reduced in number (absolute T cellcount=400/microliter); Sixteen percent of his PBL were Leu 2a+, 9% were3a+, and 16% were SIg+. Lymph node biopsy revealed depletedparafollicular zones. Proliferative responses to the T cell mitogens PHAand Con A were markedly reduced (PHA-1244 cpm ¹⁴ C TdR vs 29,290 cpm fora normal control, Con A-386 cpm vs 13,350 cpm). Based on these findings,the diagnisis of Nezelof's syndrome was made.

At the age of 31/2, he developed Mycobacterium avium penumonitis andCandida esophagitis. He was referred to our institution for a Tcell-depleted marrow graft from his HLA haploidentical half-brother withthe use of the lectin separation technique of Reisner et al. [(1980)Lancet 2: 1320]. The initial in vitro studies described here wereperformed before grafting. No durable evidence of engraftment wasdocumented. The patient's condition deteriorated with cardiomyopathysecondary to adenovirus infection, renal failure, seizures, andaspergillus pneumonia. Because of the desperate clinical situation andevidence of improved T cell function in vitro in the presence of IL 2,highly purified IL 2 was administered subcutaneously daily in the leftthigh as part of an approved phase I investigation. Informed consent wasobtained.

The patient received five escalating doses of 0.1, 1.0, 10, 100, and 500units. His clinical condition deteriorated with several episodes ofsevere bronchospasm. Mechanical ventilation was required and the patientexpired because of respiratory failure and hypotension 8 days afterinitiation of hp IL 2 therapy. Postmortem examination revealed extensivepulmonary aspergillosis. It has been suggested retrospectively that thischild may have suffered from the acquired immunodeficiency syndrome thathas effected homosexual men, drug abusers, Haitians, and hemophiliacs[CDC Task Force (1982) N. Engl. J. Med. 306: 248]. This issue was raisedbased on the fact that the child's mother was an i.v. drug abuser andthat this infectious problems were not documented during his first 2 yrof life.

Characterization of the immunologic defect of patient J.V.: The abilityof PBL from patient J.V. to produce IL 2 was assessed by usingstimulation with PHA and the mitogenic monoclonal antibody OKT3 [Chang,T. W., et al. (1981), Proc. Nat'l. Acad. Sci. U.S.A. 78: 1805]. Asdemonstrated in Table III, after 24 hr of culture, neither stimulus wascapable of inducing IL 2 production from the PBL of this child. Incontrast, each of these mitogens regularly elicits IL 2 production fromnormal PBL. The production of IL 2 was monitored for 72-hr. Aftermitogen stimulation at no time during the 72 hour period was IL2production observed.

The effects of highly purified, exogenous IL 2 on vitro assays of T cellfunction were subsequently studied in this child. The proliferation ofpatient J.V.'s.

                  TABLE III                                                       ______________________________________                                        IL 2 production 24 hr after mitogenic stimulation                                    IL 2 Produced (U/ml)                                                                       Median production                                                Production by                                                                              and range in normal                                              Nezelof's patients                                                                         individuals                                               Stimulus J. V.      A. F.   (N = 22)*                                         ______________________________________                                               U/ml                                                                   OKT3     0.0        0.6     3.0 (0.9-16)                                      PHA      0.0        0.6     2.1 (0.8-6.8)                                     ______________________________________                                         *N = the number of normal individuals studied                            

PBL in response to OKT3 and PHA in the presence and absence of exogenousIL 2. The inability of this patient's cells to sustain proliferationbeyond 48 hr is corrected when exogenous IL 2 is added, with anapproximately 10-fold increase in proliferation. In a normal individual,addition of hp IL 2 does increase proliferation somewhat, but incontrast to the patient, there is less than a twofold increase. Highlypurified IL 2 in the absence of a mitogenic stimulus does not inducesignificant proliferation of normal PBL during the first 72 hr ofculture. (After 5 to 6 days of in vitro culture, some augmentation ofthymidine uptake is seen).

The effects of exogenous hp IL 2 on in vitro MLC are summarized in TableIV. In Table IVA, the responses of patient J.V. are shown. The patient'sPBL were sensitized with pooled PBL from 10 normal individuals in orderto provide maximal allogeneic stimulation. In the absence of hp IL 2,J.V. demonstrates minimal to absent proliferation. When hp IL 2 isadded, the response is boosted 4.5- to 13-fold. As shown in MLCexperiment 2, the irradiated stimulator pool does not contribute to theobserved proliferation. Normal individuals after 6 days are shown inTable IVB. In contrast to the patient, normal individuals do not showsignificant augmentation of alloantigen-induced proliferation in thepresence of exogenous hp IL 2. This is evident with the use ofstimulation with either PBL from a single unrelated person or with apool of PBL from 10 individuals. In contrast, the response to autologousstimulation is boosted when exogenous IL 2 is added. Exogenous hp IL 2also does not appear to accelerate or otherwise alter the kinetics ofthe MLC response to alloantigen.

                  TABLE IV                                                        ______________________________________                                        In vitro effects of highly purified human IL 2 on                             mixed lymphocyte culture response*                                            ______________________________________                                        A. PBL - J. V. (Nezelof's Syndrome)                                                       Stimulator PBL                                                    Respondor PBL Pool.sub.x                                                                              JV-PBL.sub.x                                                                           Medium                                       ______________________________________                                        MLC 1                                                                         J. V. (PBL) + IL2                                                                           6,048     676      440                                          J. V. (PBL)     466     152      148                                          MLC 2                                                                         J. V. (PBL) + IL2                                                                           6,442     1,400    1,178                                        J. V. (PBL)   1,464     812      984                                          Pool.sub.x medium + IL2                                                                     --        --       246                                          Pool.sub.x medium                                                                           --        --       142                                          ______________________________________                                        B. Normal PBL                                                                          Stimulator PBL                                                       Responder PBL                                                                            NC1.sub.x                                                                             NC2.sub.x                                                                             Pool 1.sub.x                                                                        Pool 2.sub.x                                                                        Medium                                 ______________________________________                                        NC1          476   11,139  19,402                                                                              19,202                                                                                448                                  NC1 + IL 2  5,532  12,358  16,067                                                                              13,986                                                                              2,069                                  NC2        10,255    363   14,936                                                                              18,241                                                                                332                                  NC2 + IL 2 10,327   3,451  15,220                                                                              13,780                                                                              1,076                                  ______________________________________                                        C. PBL - A. F. (Nezelof's Syndrome)                                                      Stimulator PBL                                                     Responder PBL                                                                              Pool.sub.x                                                                            Unrelated.sub.x                                                                         PBL.sub.x                                                                           Medium                                   ______________________________________                                        A. F. (PBL) + IL 2                                                                         9,154   9,406     8,314 8,674                                    A. F. (PBL)  1,692   642         736   632                                    Medium + IL 2                                                                                150   158       ND    ND                                       Medium         144   164       ND    ND                                       ______________________________________                                        D. PBL - A. W. (SCID)                                                                    Stimulator PBL                                                     Responder PBL                                                                              Pool.sub.x                                                                            Unrelated.sub.x                                                                         PBL.sub.x                                                                           Medium                                   ______________________________________                                        A. W. (PBL) + IL 2                                                                         666     414       316   292                                      A. W. (PBL)  342     316       274   288                                      Medium + IL 2                                                                              302     208       ND    ND                                       Medium       230     182       ND    ND                                       ______________________________________                                         *MLC induced proliferation of PBL from patients J. V., A. F., and A. W.       and two normal individuals in the presence and absence of highly purified     IL 2. x denotes irradiated (4000 rads) stimulator cells. Pool denotes PBL     from 10 normal donors. The data represents median triplicate values of cp     after 24hr pulse labeling with [.sup.3 H]Tdr (120 to 144 hr).            

The effect of exogenous hp IL 2 on the generation of cytotoxic effectorcells by patient J.V. is shown in Table VA. Freshly harvested PBL fromJ.V. without in vitro stimulation exhibited low but normal levels of NKactivity vs the NK-sensitive target K562, but no cytotoxic T cellactivity vs PHA lymphoblasts. After 6-day in vitro sensitization vs anallogeneic pool of PBL in the absence of IL 2, no viable cells wererecovered. A similar sensitization in the presence of hp IL 2 resultedboth in the generation of cytotoxic T cell activity against PHAlymphoblasts and augmented NK-like cytotoxicity against K562. In normalindividuals, hp IL 2 produces minimal augmentation of cytotoxicity inmixed lymphocyte cultures, employing pooled alloantigenic stimulation(Table VB). However, with a submaximal stimulation using PBL from asingle unrelated donor, T cell-mediate cytotoxicity against PHAlymphoblast targets is augmented in normal individuals as well.

Results of in vivo trial of highly purified IL 2 in patient J.V.: Asdetailed in the case history, patient J.V. received a brief in vivotrial of subcutaneous hp IL 2. Although the patient succumbed to severepulmonary infection, the postmortem examinations of this lymphoidtissues suggests that hp 2 may have exerted an in vivo effect. Incomparing photomicrographs of a lymph node draining the IL 2 injectionsites and a comparable control node from a remote site, the controlnode, which is representative of the nodes throughout the rest of thebody, reveals a striking absence of lymphocytes, with primarilyhistocytes and plasma cells being identified. The draining node, inmarked contrast, shows nests of lymphoid cells, not present in the otherlymphoid tissues. It is noteworthy that although the patient received aT cell-depleted bone marrow graft from an HLA haploidentical halfbrother, there was no evidence of residual engrafted cells at the timeof the patient's death either via cytogenetic analysis of HLA typing ofpurified T cell populations.

                  TABLE V                                                         ______________________________________                                        In vitro effects of highly purified human IL 2 on                             cell-mediated cytotoxic responses developed in 6-day MLC.sup.a                ______________________________________                                        A. J. V. - PBL (Nezelof's Syndrome)                                                               % Cytotoxicity                                                                (.sup.51 Cr Release)                                                   E:T    Target Cells                                              Effector Cells Ratio    Pool PHA.sup.b                                                                            K562                                      ______________________________________                                        J. V. PBL (before MLC)                                                                       50:1      2          28                                        (J. V. PBL) (pool.sub.x).sup.a                                                               50:1     No viable cells recovered                             (J. V. PBL) (pool.sub.x) + IL2                                                               50:1     21          45                                        ______________________________________                                        B1. Normal PBL after pooled allogeneic stimulation                                           % Cytotoxicity                                                                (.sup.51 Cr Release)                                                          Target Cells                                                   (NC1).sup.d (Pool.sub.x)                                                                E:T Ratio  Pool PHA  NC1 PHA.sup.•                                                                    K562                                  ______________________________________                                        Without   100:1      56        6        69                                    IL2       50:1       51        4        63                                              25:1       39        4        54                                    With      100:1      62        7        65                                    IL 2      50:1       56        7        61                                              25:1       52        6        57                                    ______________________________________                                        B2. Normal PBL after stimulation by                                           a single unrelated individual                                                                % Cytotoxicity                                                                (.sup.51 Cr Release)                                                          Target Cells                                                   (NC1) (NC2.sub.x)                                                                       E:T Ratio  NC2 PHA   NC1 PHA  K562                                  ______________________________________                                        Without   100:1      34        2        63                                    IL2       50:1       30        3        67                                              25:1       28        1        58                                    With      100:1      67        3        75                                    IL 2      50:1       55        3        74                                              25:1       37        3        67                                    ______________________________________                                        C. AF-PBL (Nezelof's Syndrome)                                                                    % Cytotoxicity                                                                (.sup.51 Cr Release)                                                          Target Cells                                              Effector Cells  E:T Ratio Pool PHA    K562                                    ______________________________________                                        (A. F. PBL) (pool.sub.x)                                                                      50:1      5           23                                      (A. F. PBL) (pool.sub.x) + IL 2                                                               50:1      9           77                                      ______________________________________                                         .sup.a Cytotoxic responses of patients J. V., A. F., and a normal             individual after 6 day in vitro mixed lymphocyte culture in the presence      and absence of exogenous hp IL 2.                                             .sup.b Pool PHA denotes day 3 PHA lymphoblasts from a pool of PBL from 10     normal individuals.                                                           .sup.c x denotes 4000 rads irradiation.                                       .sup.d NC1 and NC2 denote two unrelated normal control individuals.           .sup.• NC1 PHA and NC2 PHA denotes day 3 PHA lymphoblasts from PBL      of NC1 and NC2.                                                          

Case Summary--A.F.

A.F. is a 3-year-old patient with Nezelof's syndrome, who was theproduct of a normal term pregnancy and delivery. During this first 2 yrof life, he was noted to have severe eczema, bronchiolitis, and otitis,but he did not require hospitalization. At the age of 2, he developedbilateral interstitial pneumonitis as a result of enterovirus and rapid,progressive respiratory failure, requiring 2 weeks of respiratorysupport on a ventilator. Over the next 6 months, he was hospitalizedthree more times for pneumonia. In spite of prolonged administration ofantibiotics, his chest x-ray failed to improve. An open lung biopsy grewHemophilus influenzae. Evaluation revealed moderate neutropenia (1000 to1500 polymorphonuclear keukocytes (PMN)/microliter) and eosinophilia. Asweat test was negative an alpha-1 antitrypsin levels were normal.Although 70% of his PBL formed E-rosettes and stained with monoclonalantibodies to the sheep red blood cell (SRBC) receptor, the majority ofthese bound only three SRBC). In contrast, only 22% of his PBL bound theT cell specific monoclonal antibody OKT3, whereas 20% bound OKT4 and 15%bound OKT8. Fifteen percent of his cells were SIg positive.

After stimulation with PHA and Con A, his proliferative responses wereonly 263 and 283 cpm ¹⁴ C TdR in contrast to the 14,700 and 9200 cpm ofcontrol PBL. Nucleoside phosphorylase and adenosine deaminase levelswere normal. Serum immunoglobulin were normal to slightly elevated(immunoglobulin G (IgG) 1516 mg/100 ml, immunolglobulin A (IgA) 155mg/100 ml, and immunoglobulin M (IgM) 285 mg/100 ml). He was, however,unable to produce specific immunoglobulin in response to pneumococcal orthphoid vaccines, although a titer of 1:32 to herpes simplex was noted.Based on these findings, Nezelof's T cell deficiency was diagnosed.

He was referred to our insititution for transplantation of fetal liverand thymus. His post-transplant course has been complicated by multipleepisodes of otitis, penumonitis, sinusitis, and a transient oosinophilicleukemoid reaction. He is presently more than 1-year post-transplantwithout any evidence of improved T cell function and without evidence ofengraftment of the fetal tissues by either HLA or cytogenetic analyses.

Characterization of the immunologic defect of patient A. F.: In responseto stimulation with PHA and OKT3, it was found that A.F.'s PBL were ableto generate 0.6U/ml of IL 2 (Table III). The effect of exogenous IL 2 onthe MLC and CML CML responses of the PBL of this child is shown inTables IVC and VC. In the absence of IL 2, minimal proliferation wasseen in response to pooled or single alloantigenic stimulation. Whenexogenous hp IL 2 was added, a substantial boost in proliferation wasseen in medium alone without alloantigen. However, no additional boostin proliferation was seen in response to the combination of allantigenplus IL 2. After 6-day MLC in the absence of IL 2, NK-like cytotoxicityagainst K562 was observed, but T cell-mediated cytotoxicity against PHAlymphoblasts was minimal to absent. In the presence of hp IL 2, NKactivity was boosted further, but significant T cell mediatedcytotoxicity was still not generated.

A.F.'s response to mitogens in the presence of hp IL 2 differed from theresponse of J.V. as well as from the response of normal individuals.Although A.F.'s PHA response was boosted sixfold, the response to OKT3increased only threefold. In contrast, J.V.'s responses to bothmitogenic stimuli were boosted over 10-fold, whereas normals wereboosted twofold or less. This differential response to PHA plus IL 2 vsOKT3 plus Il 2 was unique to A.F. This finding is in agreement with theprevious observation that the majority of A.F.'s SRBC rosettingphyphocytes lacked the OKT3 antigen.

The effects of IL 2 on MLC response in three patients with severecombined immunodeficiency (SCID): Three patients with classical SCIDwere studied to assess the effects of IL 2 on their response toalloantigen. In all three children, there was no boosted in theproliferation of their PBL above that seen in medium alone irrespectiveof the addition of alloantigen and/or hp IL 2. A representative MLCstudy from one child, A.W., is shown in Table IVD.

Early studies of the soluble factors released during immune reactionsidentified a variety of helper "activities" that could substitute for Tcells in in vitro assays [Plate, J. M. D. (1976) Nature 260: 329; Finke,J. H., et al. (1977) Nature 267: 353; Wagner, H., et al. (1978) J. Exp.Med. 148: 1523; Farrar, J. J., et al. (1978) J. Immunol. 121: 1353;Baker, P. E., et al. (1978) J. Immunol. 121: 2168; Watson, J., et al.(1979) J. Immunol. 122: 209; Watson, J., et al. (1979) J. Immunol 122:1633; Okada, M., et al. (1979) J. Immunol 122: 2527; Okada, M., et al.(1980), J. Immunol. 125: 850; and Hamaoka, T., et al. (1981) J. Immunol.126: 659]. Subsequently, it has been shown that many of these T cellhelper activities represent the effects of a single lymphokine, IL 2, inthe various assay systems employed [Gillis, S., et al. (1978), J.Immunol. 120: 2027; Watson, J. et al. (1979) J. Exp. Med. 150: 849;Gillis, S., et al. (1979) J. Immunol. 124: 1954; Kern, D. E., et al.(1981) J. Immunol. 127: 1323). The most direct demonstration of IL 2activity is via its ability to support the long-term in vitro growth ofactivated T lymphocytes [Morgan, D. A., et al. (1976) Science 193: 1007;Gillis, S. et al. (1978) Supra]. In addition, however, purified IL 2preparations have been shown to provide "help" in inducing humoralresponses to heterologous erythrocytes in nude mice (presumably viainduction of helper T cells) [Farrar, J. J., et al. (1978) J. Immunol121: 1353; Watson, J., et al. J. (1979) Immunol. 122: 209; Watson, J.,et al. (1979) J. Immunol. 122: 1633; Watson, J., et al. (1979), J. Exp.Med. 150: 849]. Exogenous IL 2 also allows thymocytes and nude mousespleen cells to develop proliferative responses to mitogen and antigenand to develop T cell-mediated cytotoxicity [Farrar, J. J., et al.(1978) Supra; Watson, J., et al. (1979) J. Immunol. 122: 1633; Watson,J., et al. (1979) J. Exp. Med 150: 849; Gillis, S., (1979) J. Immunol.124: 1954; Gillis, S. et al. (1979) J. Exp. Med. 149: 1460; Wagner, H.,et al. (1980) Nature 284: 278]. In nude mice, the inability to generateadequate amounts of IL 2 appears to play a major pathophysiologic rolein the T cell defects that are seen [Gillis, S., et al. (1979) Exp. Med.149: 1460), although this deficit may not be absolute (MacDonald, H. R.,et al. (1982) J. Immunol. 129: 521). Diminished IL 2 synthesis has alsobeen demonstrated in aged mice. Antigen-induced T cell proliferation,MLR, and CML responses that are normally impaired in these animals areall markedly enhanced when exogenous IL 2 is added [Thoman, M. L., etal. (1982) J. Immunol., 128: 2358].

Evidence has also accumulated that IL 2 is necessary for the generationof cytotoxicity by normal T lymphocytes. Metabolically inactivated (UV-or heat-treated) stimulator cells fail to induce the in vitro generationof CTL unless exogenous IL 2 is added to the culture medium [Kern, D.E., et al. (1981) J. Immunol. 127: 1323]. Addition of a monoclonalantibody to IL 2 is capable of abrogating the proliferative response ofT cells to mitogen and the development of cytotoxicity in in vitro mixedlymphocyte culture [Gillis, S., et al. (1981) J. Exp. Med. 154: 983].Taken together, these data argue quite strongly that IL 2 plays animportant role in the development of a variety of normal T cellresponses. They also suggest that some human disorders of T cellincompetence might result from defects in the production of and/orresponse to IL 2.

We have attempted to test this hypothesis by studying the effect ofhighly purified IL 2 on in vitro assays of T cell function in childrenwith primary T cell deficiencies. In one child with Nezelof's T celldeficiency, J.V., the available evidence would pointtoward an IL2-related defect. This child was deficient in his ability to product IL2. Moreover, his proliferative response to T cell mitogens andalloantigen were markedly improved when exogenous IL 2 was added.Finally, in the presence of hp IL 2, he was able to generate cytotoxiceffector lymphocytes after in vitro mixed lymphocyte culture. This childwould therefore appear to have suffered from an immunologic defectsimilar to that seen in nude or aged mice. These observations and thedesperate clinical circumstances led to the in vivo trial of hp IL 2this patient. The appearance of increased numbers of lymphocytes in thedraining lymph nodes suggests that subcutaneously administered hp IL 2produced an in vivo effect on the patient's T cells.

A different pattern of in vitro response was seen in the secondNezelof's patient, A. F. This child was less deficient in his ability toproduce IL 2 than was J.V. His cells were also less susceptible to thegrowth-promoting effects of hp IL 2 after stimulation with mitogens. InMLC, increased proliferation was seen in the presence of IL 2,irrespective of whether additional allogeneic stimulation was provided.In cytotoxicity assays, NK-like activity was strongly boosted whereas Tcell lysis of PHA lymphoblasts was not. In this context, it isnoteworthy that NK cells in mouse and man have been shown to besensitive to the growth-promoting properties of IL 2 [Dennert, G. (1980)Nature 287: 47; Nable, G., et al. (1981) J. Exp. Med. 153: 1582;Kuribayashi, K., et al. (1981), J. Immunol. 126: 2321; Sugamura, K., etal. (1982), J. Immunol. 128: 1749; Pawlec, G., et al. (1982), J.Immunol. 128: 1892; Flomenberg, N., et al. (1982), J. Cell. Biochem.(suppl. 6):25 and Kornbluth, J., et al. (1982) J. Immunol. 129: 2831].

Moreover, although T cells require activation to become IL 2 sensitive,this may not apply to NK cells (Kornbluth, J., et al. (1982) Supra).Normal individuals also show increased proliferation in response toautologous stimulation plus IL 2. Lesser degrees of proliferation arealso seen with highly purified IL 2 without autologous stimulation after5 to 6 days of culture. These responses may therefore represent theproliferation of NK cells that may not require triggering to become IL 2sensitive. This proliferative response may also partially reflect theexpansion of T cell populations previously activated in vivo. NK activecells expressing a "non-T-cell" phenotype (SRBC receptor positive butLeu1/OKT1, Leu2a/OKT8, Leu3a/LKT4, and Leu4/OKT3 negative) can be grownin conditioned medium from the peripheral blood of normal individuals[Kornbluth, J., et al. 1982 Supra; Flomenberg, N., et al. (1983), J.Immunol. 130: 2635; Herberman, R. B. (1982), Transplantation 34:1) aswell as from A.F. and other T cell-deficient patients. This child,therefore, seems to possess IL 2 responsive NK cells, but unlike J.V.,his T cell defect cannot be attributed solely to subnormal IL 2production. A.F. would therefore appear to be suffering from a differentpathophysiologic defect that J.V. The variation between these twopatients illustrates the potential utility of this type of immunologicphenotyping in characterizing immune defects. Although initially felt tobe suffering from the same clinical disorder, these children clearly haddifferent pathogenetic defects underlying their T cell deficiencies.Clearly, other cytokines derived from either monocytes or T cells areinvolved in the generation of T cell response (Larsson, E. L., et al.(1980) Nature 283: 664, Raulet, D. H., et al. (1982) Nature 296: 754).As these various factors become available in relatively pure form and insufficient quantity, further dissection of clinical T cell defects maywell become possible.

None of the children with SCID demonstrated any change in theirproliferative response in MLC in the presence of hp IL 2. A recent study(Lopez-Botet, M., et al. (1982), J. Immunol. 128: 679) reported anabsence of IL 2 synthesis in SCID. In addition, this study demonstratedthat exogenous IL 2 did not alter the proliferative response to PHAstimulation in SCID. These combined results suggest that both theproduction of the response to IL 2 are impaired in this disease.

Only one of these five children with primary T cell deficienciestherefore had the combination of a defect in endogenous IL 2 production,but preservation of the ability to respond to exogenous IL 2. In thischild, that IL 2 was capable of exerting some in vivo effects on Tlymphocytes. These findings together raise the possibility that purifiedcytokines may ultimately have therapeutic potential in appropriatelyselected patients with immune deficiency states. We have recently hadthe opportunity to study an additional patient with Nezelof's syndrome.This child's proliferative and cytotoxic responses to alloantigen withand without hp IL 2 were strikingly similar to those of A.F.

Interleukin 2 (IL2), also known as T cell growth factor, can be producedby cell subsets (Meuer, S. C., et al., (1982), J. Immunol. 129: 1076;Welte, K., et al. (submitted) OKT8 antibody inhibits OKT3 induced IL 2production and proliferation in OKT8+ cells.) and NK cells in responseto mitogenic or antigenic stimulation. The same stimulus also leads toexpression of IL2 represents on IL2 responder cells, which can be of anyT cell or of NK cell subtype [Meuer, S. C., et al. (1982) Supra; Welte,K., et al. (submitted) Supra; Domzig, W., et al. (1983) J. Immunol. 130:1890; Flomenberg, N., et al. J. Immunol. in press]. The binding of IL2to its receptor on approximately activated responder cells leads to cellproliferation an clonal expansion of the activated responder cellsubset(s) [Meuer, S. C., et al. (1982) Supra; Welte, K., et al.(submitted) Supra; Domzig, W., et al. (1983) J. Immunol. 130: 1970;Flomenberg, N., et al. J. Immunol. in press; Welte, K., et al. (1982) J.Exp. Med. 156: 454].

Beyond its physiological role in maintaining and expanding cell mediatedimmunity, alterations in IL2 production and response have beenpostulated to play a pathophysiological role in certain lymphoidleukemias [Rucetti, F. W., et al. (1981) Blood 57: 379; Mertelsmann, R.,et al. (1981) Blut 43: 99; Venuta, S., et al. (1983), Blood 61: 781].

Since T cells and NK cells are considered to play an important role inthe immune responses to tumor cells and infectious agents, weinvestigated (a) endogenous IL2 production, (b) proliferative responseto endogenous IL2, as well as (c) the proliferative response to highlypurified human IL2 (HP IL2) in a variety of human leukemias andimmunodeficiency states (IDS). In the majority of patients, defectivemitogen responses were found to be associated with IL2 productiondefects [Ciobanu, N., et a. (1983) J. Clin. Immunol. 3: 332; Welte, K. ,et al. (in press) Human Interleukin 2 in Modern Frends in Human LeukemiaV, Springer Verlag, N.Y.]. Furthermore, addition of highly purifiedhuman IL2 [Welte, K., et al. (1982), J. Exp. Med. 156: 454] led to atleast partial correction of diminished in vitro proliferation in themajority of these patients [Ciobanu, N., et al. 1983 Supra; Welte, K.,et al. (in press) Human Interleukin 2 Supra; Flomenberg, N., et al.(1983) J. Immunol. 130: 2644]. Based on these observations, in vivoanimal studies and combined phase I and II clinical trial of human IL 2were initiated.

Highly Purified Human IL2 (hpIL2)

IL2 was purified 40,000-fold from human lymphocyte CM, costimulated withDaudi cells as previously described in detail above (Welte, K., et al.1982 Supra). The IL2 exhibited a single peak of 14,500 daltons bySDS-PAGE and HPLC. The specific activity of the final product was 10⁶U/mg protein. The IL2 assay and definition of units were as describedpreviously above (Welte, K., et al. 1982 Supra). The hp IL2 preparationwas sterile and nonpyrogenic, both in the limulus assay and in rabbits.In preliminary toxicity studies, hpIL2 was found to be non-toxic in mice(5,000 U/day×15 days, equivalent to 600,000 U/m² ×15 days). It is freeof CSF, BGF, BIF, i.e. colony-stimulating factor, B cell growth factorand B cell inducing factor (also previously known as T cell replacementfactor and BDF) respectively, alpha and gamma-interferon activities andis biologically active in vitro on both human and murine IL2 respondercells.

Further Studies of Correction of Immunodeficiency States in Man byhighly purified IL2 (hpIL 2) Expansion of Cytotoxic Precursors by hpIL2in mice

C57BL/6 mice (2-12 per group) were given injections of L1210 tumor cells(5×10⁵, s.c.) in the hind flank. Cyclophosphamide was administered (i.p.180 mg/kg) 24 hr after tumor cell inoculation. On the 7th day aftertumor implant, the inguinal nodes were removed and the cells werewashed, counted and mixed with ⁵¹ -Cr-labelled target cells in a 5-hr ⁵¹Cr release assay. This in vivo lymph node assay elicits a localcytotoxic response with no detectable cytotoxic activity in thecontralateral node or spleen. In mice receiving IL2, hpIL2 was infusedsubcutaneously by the use of osmotic infusion pumps (Alza Corp., PaloAlto, CA). Details of the experimental protocol have been describedelsewhere [Merluzzi, V.J., et al. (In press) J. Immunol.].

In Vitro Studies In Man

Patients with the disease categories detailed in Table VII were followedat Memorial Hospital. Ten ml of heparinized blood was drawn uponobtaining informed consent. Lymphocytes were separated and phenotyped aspreviously described (Venuta, S., et al. (1983), Blood 61: 781). Cellproliferation was measured in the absence and presence of 10 U/ml hpIL2on day 3 upon stimulation with medium alone (RPMI 1640, 10% fetal calfserum), PHA, OKT3 or PAN T2.

Pan T2 is an IgG1 anti-human T cell monoclonal antibody which reactswith a different epitope of the same antigenic complex that isrecognized by OKT3 (Venuta, S., et al. (1983) Supra). Supernatants ofidentical cultures were harvested after 24 hours and accessed forendogenous IL2 production as described above.

Phase I Trial In Man

Standard phase I criteria for patient selection were used. The protocolwas approved was approved by the Institutional Review Board. Informedconsent was obtained from each patient. To be eligible for this studypatients were required to show in vitro (a) defective proliferativeresponses to at least one of three mitogens (PHA, monoclonal antibodiesOKT3, Pan T2), and (b) at least a 100% increment of proliferativeresponse upon addition of IL2 (10 U/ml) in at least one of the threemitogen assays.

IL2 was administered subcutaneously to achieve maximum lymphaticdrainage. In the first phase of the study (Phase A: "toxicity screen"),three patients were treated with escalating doses. In the first patient,dosages were increased daily to a maximum of 1,000 U/day. In the twosubsequent patients, IL2 was administered subcutaneously by 24 hrinfusion to more closely parallel the mode of administration used in theanimal study. Dosages in these two patients were escalated every 3rd daystarting at 300 U to a maximum of 4,000 U/day for 3 days over a total of21 days. Since no toxicity was seen in these three patients, subsequentpatients received IL2 at a constant daily dose s.c. for two weeks,followed by a two-week treatment-free interval. Dosages were escalatedeither in patients already on study after the two-week treatment-freeinterval or in patients newly entering the study.

Because of logistic considerations, hp IL2 was administered as a singledaily s.c. injection. When starting on hpIL2 for the first time, thepatient received an intradermal test-dose of 100 U and in the absence ofany local reaction received the full dose one hour later. Following thefirst dose of IL2, vital signs were monitored every 30 min for 4 hours.In vitro tests performed at weekly intervals included complete bloodcounts, differential and reticulocyte count, T cell proliferation inresponse to PHA, OKT3 and Pan T2 in the presence and absence of 10 U/mlhpIL2 (Ciobanu, N., et al. 1983 Supra) cell surface marker studiesincluding OKT3, OKT4, OKT8 and Leu 4 (Venuta, S., et al. 1983 Supra;Ciobanu, N., et al. (1983) Supra) as well as determination of NKactivity with K562 as target (Flomenberg, N., et al. (in press) J.Immunol.). Details of the various techniques have been described (Welte,K., et al. (submitted) Interleukin 2; Domzig, W., et al. (1983) Supra;Flomenberg, N., et al. (in press) Supra; Welte, K., et al. (1982) Supra;Mertelsmann, R., et al. (1981) Blut 43: 99; Venuta, S., et al. (1983)Supra; Ciobanu, N., et al. (1983) Supra; Welte, K., et al. (in press)Supra; Flomenberg, N., et al. (1983) J. Immunol. Supra; Merluzzi, V. J.et al. (in press) J. Immunol.). Every two weeks, biochemical screeningprofile, serum immunoglobulins, immunoelectrophoresis, PT, PTT andurinalysis were performed.

The clinical trial was designed to yield information on both, potentialtoxicity (phase I) as well as biological activity and efficacy (PhaseII). While standard phase I/II chemotherapy studies are based on thepresumption that maximum tolerated dose levels are also the mostefficacious dose levels, this hypothesis might not extend to trials ofbiological response modifiers.

Murine Studies

Cyclophosphamide (CY) has been shown to be one of the most potentanti-cancer agents available. However, its strong immunosuppressiveproperties limit its full potential, since several studies have shownthat the use of CY as an effective antitumor agent depends upon intacthost immunity [Cheever, M. A., et al. (1980), J. Immunol. 124: 2137;Cheever, M. A., et al. (1980) J. Immunol. 125: 711; Lubet, R. A., et al.(1978) J. Nat'l. Cancer Inst. 61: 897; Moore, M., et al. (1973) Int. J.Cancer 11: 358).

Spleen cells from mice treated with high single doses of CY are unableto generate normal cytotoxic T-lymphocyte (CTL) response in vitro(Merluzzi, V. J., et al. (1981) Cancer Res. 41: 850). This low response,however, can be reconstituted by the addition of T helper cells to theculture system (Merluzzi, V. J., et al. (1980) Int. J. Immunopharmacol2: 341) or crude mixed lymphocyte culture (MLC) supernatants (Merluzzi,V. J., et al. (1981) Supra).

Since production of helper and differentiation factors for ytotoxiccells is one of the properties of T-helper cells and IL2 is one of thepredominant lymphokines generated in MLC, we have analyzed human hpIL2for its ability to recover in vitro and in vivo cytotoxic activity inmice pre-treated with high single doses of CY. These high doses of CYhave been shown to be very active against murine L1210 leukemia (SkipperH. E., et al. (1964) Cancer Cancer Chemother Rep. 35: 1), but also to behighly immunosuppressive (Merluzzi, V. J., et al. (1981) Cancer Res. 41:3663). We have selected highly purified human IL2 because hpIL2 is themost highly purified IL2 available and is active on murine lymphoidcells (Welte, K., et al. (1982) J. Exp. Med. 156: 454). In addition,this in vivo experimental system should serve as a relevant pre-clinicalmodel for a clinical trial of hpIL2 in immunosuppression caused byanti-neoplastic therapy.

Mice and Cell Lines. Male C57BL/6 (H-2^(b)) and DBA/2 (H-2^(d)) micewere obtained from the Jackson Laboratory, Bar Harbor, ME. P815-X2(H-2^(d)) mastocytoma cells and L1210-CYR (H-2^(d)) leukemia cells weremaintained by weekly i.p. passage in syngeneic DBA/2 mice. The L1210-CYRcell line is a CY-resistant subline of L1210 and described previously[Merluzzi, V. J., et al. (1981) Cancer Res. 41: 3663]. The AKSL thymomacell line (H-2^(k)), derived form a spontaneous AKR leukemia, and theYAC lymphoma cell line (H-2^(d/k)) were maintained by in vitro passagein RPMI 1640 culture medium containing 10% fetal calf serum (FCS). TheP815, L1210-CYR and AKSL cell lines are insensitive to classical naturalkiller (NK) cells. The YAC cell line is sensitive.

Preparation of Spleen Cells. C57BL/6 spleen cells were prepared for invitro culture in a manner similar to that described by Mishell andDutton [(1967) J. Exp. Med. 126: 423]. Briefly, spleens were asepticallyremoved and gently teased into suspension in balanced salt solution(BSS). Large debris were allowed to settle at 0° C. for 5 min, and thecells remaining in the supernatant were aspirated, washed 3 times inBSS, and adjusted to the desired concentration in RPMI 1640 (GrandIsland Biological Co., Grand Island, NY) containing 5×10⁻⁵ M2-mercaptoethanol and 10% specifically-screened heat-inactivated (56°C., 30 min) FCS.

Determination of cytotoxic activity. Cytotoxic activity was measured bya modification of the ⁵¹ Cr release assay as described by Baum andPilarski [(1978) J. Exp. Med. 148: 1579]. Briefly, 2-4×10⁶ tumor targetcells were mixed with 250 microCi ⁵¹ Cr (New England Nuclear, Boston,MA) in a volume of 0.6 ml in RPMI 1640 medium and incubated for 1 hr.After washing and counting, 100 microliters containing 5×10³ 51Cr-labeled target cells were added to each culture well. The respondercells were harvested, washed and counted in incubated at several L/Tratios with ⁵¹ Cr-labeled target cells in microculture plates. Thecultures were mixed with a multichannel pipettor, centrifuged for 3 minat 30×g, and then incubated at 37° C. for 5 hr in a humidifiedatmosphere with 5% CO₂. At the end of 5-hr incubation period, the plateswe centrifuged at 400×g for 5 min, and the amount of radioactivityreleased into 0.1 ml of the supernatant of each culture was determinedin a Nuclear Chicago gamma counter. The percentage of specific ⁵¹ Crrelease on quadruplicated cultures was calculated in the followingmanner: ##EQU2## Total releasable counts were determined by diluting the⁵¹ Cr-labeled target cells in distilled water. Spontaneous release forthe 5-hr assay was less than 20%.

In vivo generation and assay of cytotoxic cells. C57BL/6 mice (2-12 pergroup) were given injections of L1210-CYR tumor cells (5×10⁵,subcutaneously) in the hind flank. CY was administered (i.p. 180 mg/kg)24 hr after tumor cell inoculation. On the 7th day after tumor implant,the inguinal nodes were removed and the cells were washed, counted, andmixed with ⁵¹ Cr-labeled target cells in a 5-hr ⁵¹ Cr-release assay asdescribed above. This in vivo lymph node assay elicits a local cytotoxicresponse with no detectable cytotoxic activity in the contralateral nodeor spleen.

When cytotoxic activity was measured at several lymphocyte:target cellratios, cytotoxic activity was quantified as a function of the logarithmof the effector:target cell ratio. The data was plotted and theeffector:target cell ratio necessary to obtain 33% lysis wasextrapolated from the linear portion of the curve. This number ofeffectors was arbitrarily taken as a "lytic unit" (L.U.). The number ofL.U./10 effectors was calculated.

IL2 infusion in vivo. IL2 was infused subcutaneously by the use ofosmotic infusion pumps (Alza Corp., Palo Alto, CA). Mice wereanesthetized (325 mg/kg chloral hydrate) for a period of 20-30 min. Themice were shaved (from right ear and midback to the posterior section ofthe rib cage) and the skin was then washed with 70% ethanol. From abovethe shoulder blade, the shaved skin as pinched between the thumb andindex finger and a small disc-shaped incision was made. The incision wasthen further extended to the Panniculus carnosus layer. Hemostats wereinserted into the incision and used to create a subcutaneous troughextending to the right inner thigh. The minipump was then insertedportal-end first anterior to the right inguinal lymph node. The wouldwas then closed with two 9 mm would clips (Clay Adams, Parsippany, NJ).All procedures were accomplished with sterile instruments and materials.The osmotic minipumps were weighed before and after filling with IL2 andall infusion pumps were cut in cross section at the end of eachexperiment to check for complete elution of IL2. The weight of theminipumps was subtracted from the total weight of each mouse wheninjecting CY on a mg/kg basis. Preliminary experiments have shown thatanesthesia and/or insertion of pumps had no effect on generalimmunological parameters of immune reactivity (antibody production andCTL generation). Several lots of osmotic pumps were previously checkedfor in vitro elution of IL2 into tissue culture medium and all wereshown to be positive. Empty or RPMI-filled osmotic pumps did not alterthe in vivo CTL response. The pumps were implanted 2 hr. before tumorcell inculation.

Cyclophosphamide. The sterile CY-sodium chloride preparation (MeadJohnson & Co., Evansville, Ind) was dissolved in distilled water to aconcentration of 20 mg/ml. Individual mice were weighed and given i.p.injections of CY. All mice received a single dose of 150 mg/kg 48 hrbefore removing spleens for culture or 180 mg/kg after tumor implant forin vivo studies. There was a 40-75% reduction in spleen and lymph nodecellularity after CY treatment. The lymphoid cells of treated mice andnormal littermate controls were more than 80% viable as determined byTrypan blue exclusion.

Anti-Thy 1.2 and Complement (C'). Lymphoid cells (10⁶ -10⁷) were treatedwith monoclonal anti-Thy 1.2 serum (1/100) obtained form Dr. UlrichHammerling (Sloan-Kettering Institute) for 45 min. at room temperature.Rabbit C' (1/12) (Cedarlane Laboratories, Hornby, Ontario, Canada) wasthen added for 45 min. at 37° C. The cells were washed in BSS, countedand adjusted to the desired concentration in RPMI tissue culture medium.

Initial experiments were designed to test the effect of hpIL2 on NKeffector cell activity in a 5-hr ⁵¹ Cr-release assay. Normal C57BL/6spleen cells and spleen cells from CY-treated mice were not able to lysethe NK insensitive P815 target in the absence or presence of IL2, whilethe YAC target was effectively lysed by all fresh effector cells. Therewas no appreciable difference in lytic activity against YAC in theabsence or presence of IL2 at the concentration used (25 U/ml) and NKeffector cells were not affected by previous treatment with CY. When thespleen cells were cultured for 72 hr with or without IL2, differences inlytic activity became apparent (Table VIA).

Spleen cells from normal mice or mice pretreated with CY and culturedalone displayed very little lytic activity against P815 and YAC targetcells. If the spleen cells were cultured in the presence of highlypurified human IL2, both P815 and YAC target cells were effectivelylysed by both normal and CY-pre-treated spleen cell preparations. Theseresults indicate that CY does neither eliminate NK effector cells northe precursors that lead to cytotoxic activity driven by purified IL2 invitro.

The fresh NK effectors were not eliminated by treatment withX-irradiation or anti-Thy 1.2 and C' before analysis in the Cr releaseassay. Spleen cells cultured for 72 hr in the presence of purified IL2,however, were no longer able to express lytic activity to NK-sensitive(YAC) or NK-insensitive (P815, L1210-CYR) target cells after treatmentwith anti-Thy 1.2 and C'.

                  TABLE VIA                                                       ______________________________________                                        Effect of highly Purified Human IL2 on Cytolytic                              Effector Cells                                                                             % specific .sup.51 Cr release                                    Effector Cells.sup.a                                                                    IL2.sup.b                                                                              YAC       P815    L1210-CYR                                ______________________________________                                        B6        -        .sup. 15 + 0.4.sup.c                                                                     3 + 0.2                                                                              1                                        B6        +        56 + 1.5  37 + 1.9                                                                              28 + 0.8                                 B6-CY     -        1          1 + 0.3                                                                              1                                        B6-BY     +        55 + 2.9  66 + 0.9                                                                              53 + 2.1                                 ______________________________________                                         .sup.a Effector cells were derived from normal (B6) or CYtreated B6 mice      (B6CY) and cultured for 72 hr in the presence or absence of IL2.              .sup.b 25 U/ml                                                                .sup.c Mean + S.E.M. of quadruplicate cultures.                          

These results suggest that IL2 can activate precursors of cytotoxiccells in vitro, and that the effector cells are thymus-derived T cells,active against both, NK-sensitive and NK-insensitive target cells.

Initial experiments were designed to test the effect of human hp IL2 onthe generation of splenic cytotoxic cells in vitro. In vitro culturedspleen cells from both normal and CY-pretreated mice did not elicitcytotoxic activity to P815 target cells in the absence of alloantigen.When mitomycin C-treated P815 target cells in the absence ofalloantigen. When mitomycin C-treated P815 stimulator cells were presentin the culture system, spleen cells from normal C57BL/6 mice generatedeffective cytotoxic activity whereas spleen cells from CY-treated didnot. When human IL2 as present in the culture system, low doses(3.125-12.5 U/ml) restored cytotoxic activity to CY-treated spleen cellswhen P815 stimulator cells were present in the cultures. When high dosesof IL2 (50 U/ml) were used, nonspecific cytotoxic activity was seen.That is, spleen cells from both normal and CY-treated mice elicitedcytotoxic activity in the absence of alloantigen. In both cases, theprecursors of the cytotoxic effector cells were resistant to CYpretreatment. Both specific and nonspecific cytotoxic effector cellsgenerated in vitro were sensitive to anti-Thy 1.2 and C'.

We next investigated the effects of highly purified human IL2 oncytotoxic cell generation in vivo. hp IL2 alone, in the absence ofantigen, was not sufficient to generate nonspecific cytotoxic cells invivo. In addition, IL2 administered to normal mice in combination withantigen either did not alter lytic activity of suppressed cytotoxicactivity. If the mice were immunosuppressed by CY, however, lyticactivity was restored by the infusion of IL2 (Table VII). The effectorcells were again, as in vitro, Thy 1.2 positive but unlike the in vitroresponses, lytic activity was specified for L1210-CYR. Further studiesexplore different dose schedules of IL2 to assess the effect of higherIL2 concentrations on NK cell and non-specific cytotoxic effector cellactivities in vitro and in vivo.

                  TABLE VII                                                       ______________________________________                                        In Vivo Effect Of Highly Purified Human IL2 On Cytotoxic                      Activity Against L1210-CYR Target Cells                                                 % Specific .sup.51 Cr Release                                       Group.sup.a                                                                         IL2       25/1.sup.c                                                                              12.5/1  6.25/1 L.U..sup.b                           ______________________________________                                        B6    --        .sup. 45 + 1.0.sup.d                                                                    31 + 1.2                                                                              15 + 1.2                                                                             14.08                                B6-CY --        16 + 1.8  12 + 0.6                                                                              10 + 0.6                                                                             0.14                                 B6-CY 0.5 U/hr  59 + 0.8  48 + 1.5                                                                              18 + 0.4                                                                             21.38                                ______________________________________                                         .sup.a B6 (salinetreated); B6CY (cyclophosphamidetreated), osmotic pumps      were inserted on day 0; L1210CYR injected 4 hr later; CY injected 24 hr       later.                                                                        .sup.b Lytic Units/10.sup.6 cells.                                            .sup.c Lymphocyte: target cell ratio                                          .sup.d Mean + S.E.M. of quadruplicate cultures                           

The following experiments were performed to test the effect of human hpIL2 in vivo. Table VIB shows the results of two experiments in whichhuman IL2 restores cytotoxic activity in lymph nodes of miceimmunosuppressed by high doses (180 mg/kg) of CY. The effector cells areThy 1.2⁺ and are specific for immunizing L1210-CYR antigen. The AKSLtarget (H-2^(k/k)) is not lysed by the effector cells. The AKSL targetis susceptible to lysis by specific anti-k/k CTL and by in vitro-inducedcytotoxic cells in the presence of high doses of IL2 Table VIC shows theresults of an experiment in which human IL2 was tested for its effectson non-tumor-bearing mice and on tumor-bearing control mice not injectedwith CY. In Table VIC Experiment #1, lymph node cells from normalC57BL/6 mice showed some natural cytotoxic activity only against theNK-sensitive YAC target cells. When IL2 was infused, the cytotoxicactivity was not enhanced and was in fact lower than the control. Thiswas again shown in Table VIC Experiment #2 where the only appreciablecytotoxic response was seen against the YAC target cell. No enhancementof cytotoxic activity was seen by IL2 infusion. Mice injected with CYalone showed similar results (Table VIC lines 5 and 6, Expt #1). Whennormal C57BL/6 mice were injected with L1210-CYR, normal cytotoxicactivity was observed with no appreciable enhancement of the cytotoxicresponse by IL2 infusion.

The experiments presented here show that highly purified human IL2stimulates cytotoxic cells in vitro and in vivo.

                  TABLE VIB                                                       ______________________________________                                        Effect of Human IL2 on Cytotoxic Activity In Vivo                                                              L.U./                                                % Specific .sup.51 Cr Release.sup.c                                                            Corr.   10.sup.6                                     Group.sup.a                                                                         IL2.sup.b                                                                             25/1.sup.f                                                                             12.5/1 6.25/1 Coef..sup.d                                                                         cells.sup.e                        ______________________________________                                        B6    --      45 ± 1.0.sup.g                                                                      31 ± 1.2                                                                          15 ± 1.2                                                                          .999  14.08                              B6-CY --      16 ± 1.8                                                                            12 ± 0.6                                                                          10 ± 0.6                                                                          .981  0.14                               B6-CY Frac-   59 ± 0.8                                                                            48 ± 1.5                                                                          18 ± 0.4                                                                          .967  21.38                                    tion V                                                                  B6    --      54 ± 0.3                                                                            33 ± 0.3                                                                          21 ± 0.8                                                                          .987  18.08                              B6-CY --      16 ± 1.2                                                                            14 ± 0.6                                                                          13 ± 1.2                                                                          .981  <.01                               B6-CY Frac-   28 ± 1.3                                                                            23 ± 0.4                                                                          19 ± 0.9                                                                          .998  3.58                                     tion VI                                                                 ______________________________________                                         .sup.a B6 (salinetreated C57BL/6); B6CY (cyclophosphamide at 180 mg/kg),      osmotic pumps were inserted on day 0; L1210CYR injected 2 hr later; CY wa     injected 24 hr later. The CTL assay was performed on day 7 after tumor        implant.                                                                      .sup.b Interleukin 2: blue agarose (Fraction V) and red agarose (Fraction     VI) delivered by infusion at 0.5 U/hr (500 U/ml).                             .sup.c 5 hr assay vs .sup.51 Crlabeled L1210CYR target cells.                 .sup.d Correlation coefficient                                                .sup.e Lytic Units/10.sup.6 cells.                                            .sup.f Lymphocyte: target cell ratio                                          .sup.g Mean ± S.E.M. of quadruplicate cultures.                       

                  TABLE VIC                                                       ______________________________________                                        Effect of Human IL2 on Cytotoxic Activity In Vivo                             (B) Non-tumor bearing mice and tumor bearing mice                             treated with saline only                                                                   % Specific .sup.51 Cr Release.sup.b                              Group.sup.a    L1210-CYR YAC        AKSL                                      ______________________________________                                        Expt 1                                                                        B6             <1        .sup. 12 ± 0.4.sup.c                                                                  .sup. h.d..sup.d                          B6 + IL2       <1         5 ± 0.4                                                                              n.d.                                      B6 × L1210-CYR                                                                         27 ± 0.1                                                                             n.d.       n.d.                                      B6 × L1210-CYR + IL2                                                                   29 ± 1.2                                                                             n.d.       n.d                                       B6-CY          <1         5 ± 0.6                                                                              n.d                                       B6-CY + IL2    <1         2 ± 0.2                                                                              n.d.                                      Expt 2                                                                        B6              3 ± 0.1                                                                             35 ± 1.5                                                                              4 ± 1.8                                B6 + IL2        3 ± 0.3                                                                             22 ± 1.7                                                                              2 ± 0.9                                ______________________________________                                         .sup.a B6 (salinetreated C57BL/6); B6CY (CY at 180 mg/kg); osmotic pumps      were inserted on day 0, L1210CYR injected 2 hr later (lines 3 + 4 only; C     was injected on day +1. The cytotoxic assay was performed on day +7. IL2      by infusion at 0.5 U/hr (500 U/ml).                                           .spsp.b.sup.51 Cr release at 5 hr; E/T = 50/1                                 .sup.c Mean ± S.E.M.                                                       .sup.d n.d. = not done                                                   

                  TABLE VID                                                       ______________________________________                                        Effect of Human IL2 on Cytotoxic Activity In Vivo                             (A) Characterization of Effector Cells                                               Treatment of Effector                                                                      % Specific .sup.51 Cr Release.sup.d                       Group.sup.a                                                                         IL2.sup.b                                                                            Cells.sup.c    L1210-CYR AKSL                                    ______________________________________                                        B6    -      none           31 ± .sup. 1.8.sup.e                                                                 <1                                      B6-CY -      none           <1        <1                                      B6-CY +      none           30 ± 1.8                                                                             <1                                      B6-CY +      C'             16 ± 2.2                                                                              n.d..sup.f                             B6-CY +      anti-Thy 1.2 + C'                                                                            <1        n.d.                                    ______________________________________                                         .sup.a B6 (salinetreated C57BL/6); B6CY (cyclophosphamide at 180 mg/kg);      osmotic pumps were inserted on day 0; L1210CYR injected 2 hr later; CY wa     injected on Day +1. The CTL assay was performed on day 7 after tumor          implant.                                                                      .sup.b Interleukin 2; red agarose (Fraction VI) delivered by infusion at      0.05 U/hr (500 U/ml).                                                         .sup.c Complement (C'); or antiThy 1.2 + C' before .sup.51 Cr release         assay.                                                                        .sup.d % .sup.51 Cr release at 5 hr; E/T = 12.5/1.                            .sup.e Mean ± S.E.M. of quadruplicate cultures.                            .sup.f n.d. = not done.                                                  

The effector cells are thymus-derived (T cells) as shown by theirsusceptibility to anti-Thy 1.2 and C' treatment. These highly purifiedpreparations of IL2 lack detectable interferon (alpha and gamma),granulocyte-macrophage colony-stimulating factor, B-cell growth factor,thymocyte differentiating activity, and were free of any contaminatingproteins judged by silver staining in SDS-PAGE. It remains to bedetermined whether lymphoid cells from normal or CY-treated mice, theIL2 preparations used, or both, contain a T-cell differentiation factorwhich has been described to act in concert with IL2 in promoting T-celllytic activity [Raulet, D. H. et al. (1982) Nature 296: 754].

Whether the effector cells for classical NK reactions and theirprecursors are different subsets of a common T-cell lineage is not yetclear. IT is clear, though, that the cytotoxic precursors are resistantto CY and therefore are able to generate lytic activity in the presenceof IL2.

We have shown that mice immunosuppressed by CY have a lower cytolyticcapacity than normal littermates. Infusion of IL2 in a rate-controlledmanner distal to the immunized lymph node enhances the low in vivocytotoxic response. The cytotoxic cells again are thymus-derivedeffectors. It is not clear why IL2 infused into normal mice with orwithout antigen administration does not enhance cytotoxic activity. Itis possible that medium components in vitro are acting together with IL2in promoting non-specific T-cell-derived effectors which cannot bedemonstrated in vivo and thus this in vitro system represents activitywhich can only be artifactual. Another possibility is differences indose response kinetics in vivo and thus this in vitro system representsactivity which can only be artifactual. Another possibility isdifferences in dose response kinetics in vivo and in vitro. Hefeneideret al. [(1982) J. Immunol. 130: 222]. We have demonstrated that in vivoadministration of murine IL2 augments alloreactive CTL as well as NKcells. We have shown augmentation of CTL only in immunosuppressed mice,but differences in IL2 concentration and use of lymph node effectorcells as opposed to splenic effectors may explain these differences.

CY is an ideal agent to combine with IL2 as an immunotherapeutic adjunctto its cytotoxic properties because in addition to being a strongantineoplastic agent, CY eliminates suppressor T cells [Rollinghoff, M.A. (1977) J. Exp. Med. 145: 455], an IL2 inhibitor [Hardt, et al. (1981)J. Exp. Med. 154: 262], and spares allocytotoxic precursors [Taswell, C.et al. (1980) Thymus 1: 1119]. It should be noted that syngeneic CTLprecursors may be more sensitive to CY than allogeneic CTL precursors[Hancock, E. J. (1982) Immunol. Immunother 14: 54 and Hurme, M. (1979)J. Exp. Med. 149: 290]. The syngeneic CY-resistant precursors can stillbe expanded however, with IL2 [Hancock et al. (1982) Supra]. The factthat CY spares some cytotoxic precursors and IL2 allows for theirdifferentiation and/or proliferation can lessen this drug's negativeimpact upon the cellular immune system.

Since lymphokine therapy for neoplasia is becoming potentially importantand much more feasible with the advent of adequate delivery systems andtechnological advances in protein purification it is possible to uethese naturally-occurring biological response modifiers in clinicaltrials. Preliminary studies in humans suggest a role for IL2 in therestoration of the chemotherapy-suppressed mitogen response in vitro, aswell as in vivo enhancement of immunological parameters in acquired andcongenital immunodeficiency syndromes. The experiments presented hereshow that if precursor cells are spared by cytoreductive agents, theimmunosuppressive effect of these agents may be counteracted in vivo bythe adequate delivery of naturally-occurring lympholines.

Precursors of cytotoxic lymphoid cells obtained from mice treated withcyclophosphamide (CY) can be expanded in culture by alloantigens in thepresence of purified human interleukin 2 (IL2). Similarly, hp IL2delivered in vivo in a rate-controlled manner enhances cytotoxicactivity in mice immunosuppressed by high doses of CY. The effectorcells are Thy 1.2 positive and are not elicited in the absence ofantigen.

In Vitro Studies in Man

IL in Lymphoid Leukemias. Several lines of evidence suggest that thegrowth of human tumors is factor dependent and that tumor cells can beresponsible for the production of these factors. We have investigatedthe possibility that the growth of certain lymphomas and leukemias isIL2 dependent and whether leukemogenesis is associated with any of thesefactors. We have investigated the possibility that the growth of certainlymphomas and leukemias is IL2 dependent and whether leukemogenesis isassociated with alterations of the mechanisms regulating IL2 productionand T cell proliferation. We have found that cALL and T ALL cellsproduce IL2 after PHA stimulation (Venuta, S., et al. 1983 Blood 61:781), and that these leukemias do not respond to the addition of Pan T2which is mitogenic and induces IL2 production in normal lymphocytes(Venuta, S., et al. (1983) Supra). Daudi, a B lymphoblastoid line, isable to rescue the response of ALL to Pan T2 (Venuta, S., et al. (1983)Supra). These results indicate that leukemogenesis induces an alterationof the molecule which is recognized by Pan T2 and responsible for Pan T2induced IL2 production. Since ALL cells present in the peripheral blooddo not proliferate detectably in suspension culture in response to IL2,we hypothesized that IL2 is required by leukemic stem cells in order toproliferate and differentiate into more mature IL2 producing leukemiccells (Venuta, S, et al. (1983) Supra). Experiments demonstratingIL2-dependence of colony formation in the cALL cloning assay (Izaquirre,C. A., et al. 1981, Blood 57: 823) support this conclusion (Feldman etal., submitted).

IL2 in Immunodeficiency States (IDS). Table VIII summarizes the cellproliferation and IL2 data in the patient groups studied. Defectiveproliferation of peripheral blood T cells in response to mitogens wasfound to be associated with defective IL2 production in all cases.Addition of IL2 at a concentration of 10 U/ml, which we found to besaturating for normal T lymphocytes tested under these conditions,restored cell proliferation partially or completely in the majority ofpatients.

                  TABLE VIII                                                      ______________________________________                                        IL2 Production and Proliferation +/-IL2 In                                    Immunodeficiency                                                                       PHA (0.5%, v/v)                                                                            OKT3 (1.25 ng/ml)                                                IL2  -IL2    +IL2    IL2  -IL2  +IL2                                 Diagnosis  U/ml cpm × 10.sup.3                                                                    U/ml cpm × 10.sup.3                           ______________________________________                                        AIDS.sup.b 1.1    20      28    0.9  13    32                                 Hemophilia nt.sup.a                                                                             52      58    nt   26    56                                 CVI.sup.c                                                                     IL2 responders                                                                           0.6    43      78    0.5  32    55                                 IL2        0.9    14      18    0.5  16    16                                 non-responders                                                                BMT.sup.d  0.2     5      24    0.2   8    51                                 Hodgkin's  nt.sup.                                                                               5      13    nt    4    17                                 Controls   2.3    78      90    3.5  61    82                                 ______________________________________                                         .sup.a not tested.                                                            .sup.b acquired immunodeficiency syndrome                                     .sup.c common variable immunodeficiency                                       .sup.d bone marrow transplantation                                       

The relative increase of T cell proliferation achieved by addition ofIL2 was significantly higher in all patient groups as compared tocontrols.

In a recent detailed analysis of IL2 production and response in theacquired immunodeficiency syndrome (AIDS), OKT3 appeared to be the mostsensitive mitogenic stimulus to identify a proliferative T cell defect(Ciobanu, N., et al. (1983) Supra). Furthermore, the degree ofproliferation in response to OKT3 appeared to be of prognosticsignificance. Patients incorporating less than 13,000 cpm in response toOKT3 exhibited significantly shorter survival than those with more than13,000 cpm. It is of interest, that in vitro T cell proliferation couldbe boosted to more than 13,000 cpm by hp IL2 in all patients studied.Although the in vivo significance of this phenomenon remains to bedetermined, it provides a further rationale to attempt to restoredefective T cell proliferation in vivo by administration of hpIL2.

Recently an aggressive form of Kaposi's sarcoma (KS) as well as anoutbreak of opportunistic infections, mainly with Pneumocystis cariniiand herpes-viruses, has been described in young homosexual males,reaching almost epidemic proportions in New York City and California[Friedman-Kien, A, et al. (1981), Morbid Mortal Weekly Rep. 301:305-308; Siegal, FP, et al. (1981), N. Engl. J. Med. 305: 1439-1444;Gottlieb, MS, et al. (1981), N. Engl. J. Med. 305: 1425-1431; Reiner,NE, et al. (1982), Ann Intern Med. 96: 170-173]. Several studies haveshown that these homosexuals with or without KS exhibit T-celldysfunction, described as an increase in the percentage ofsuppressor/cytotoxic T-cell subpopulations (Gottlieb, MS, et al. (1981)Supra) or as a lower-than-normal ratio of helper to suppressor cells(Koziner, B, et al. (1982), N. Engl. J. Med. 306: 933-934). Others foundabsent mitogen responses of peripheral blood lymphocytes (PBL) fromhomosexuals with KS and depressed natural killer-cell activity (Siegel,FP, et al. (1981), Supra).

It has been previously shown that the proliferative response to Tlymphocytes to mitogenic (or antigenic) stimulation is dependent uponthe release of a low molecular weight protein designated interleukin 2(IL2) (Ruscetti, FW, et al. (1981), Blood 57: 379-394). This laboratoryhas previously reported on the use of the T-cell-specific mitogenicmonoclonal antibodies, OKT3 and Pan T2, in the analysis of IL2production and response in human disease states [Venuta, S, et al.(1982), in UCLA Symposia in Molecular and Cellular Biology Vol. XXIVeds. E. Viteta and C. Fred. Fox, New York, Academic Press, pp. 253-259].Both reagents are able to induce IL2 release, expression of IL2receptors, and, as a result, lymphocyte proliferation (Venuta, S, et al.1982 Supra).

In view of the evidence that T lymphocytes from homosexual patients withKS have suboptimal proliferative responses to mitogen stimulation, aswell as the data demonstrating a decrease in helper T cells, we studiedthe effect of both phytohemagglutinin (PHA) and mitogenic antibodystimulaion on T-cell proliferation and IL2 production in peripheralblood lymphocytes from homosexuals with and without KS.

Patient Population. We have tested the peripheral blood mononuclearcells from 21 homosexual patients seen in the outpatient department atMemorial Hospital in the spring and summer of 1982 (Table XI). Twelve ofthem had biopsy-proven KS. Four patients had only generalizedlymphadenopathy of a "reactive type" but were otherwise healthy. Theremaining five patients had different opportunistic infections. None ofthe patients with either lymphadenopathy or opportunistic infections hadassociated KS. The herpes titers and T-cell characteristics of thepatients as well as survival data are listed in Table X. As controls weused 10 healthy heterosexual males, matched for age.

Lumphocyte Separation and Identification. The mononuclear cells fromheparinized blood samples were separated b Ficoll-Hypaque densitygradient centrifugation and used immediately. The lymphocyte fractionwas reacted with a panel of anti-T-cel monoclonal antibodies (OrthoParmaceuticals, Raritan, NJ) that recognized all peripheral T cells(OKT3), helper T cells (OKT4), or suppressor T cells (OKT8) [Reinherz,EL, et al. (1979), N. Engl. J. Med. 301:1018-1022]. The percentage ofcells binding specific mouse monoclonal antibodies was determined byindirect immunofluorescence on a cytofluorograph system 30 (OrthoInstruments).

Mitogen Stimulation of Lymphocytes. RPMI-1640 supplemented with 10%heat-inactivated fetal calf serum was used to prepare incubation mediacontaining the following mitogens: (a) phytohemagglutinin (PHA; M form;GIBCO, Grand Island, NY), final concentration 0.5%; (b) OKT3 monoclonalantibody (Ortho, Raritan, NJ), final concentration 1 ng/ml; (c) Pan T2is monoclonal antibody [produced by our laboratory [Wang, C. Y., et al.(1983) (submitted for publication)] final concentration 100 ng/ml.Briefly, Pan T2 is an IgG₁ anti-human T-cell monoclonal antibody whichreacts with more than 90% human peripheral T lymphocytes and thymocytes,while it is unreacting with B cells, monocytes, granulocytes andplatelets. All mitogen concentrations were chosen after appropriatetitration experiments to induce a maximum proliferative response [Wang,CY, et al. (1983) (submitted for publication)].

Mononuclear cells of patients and controls were tested for proliferationand IL2 production using the mitogen-containing media and media only ascontrol. Proliferation was measured by [³ H] thymidine incorporation aspreviously described above (Welte, K, et al. (1982) J. Exp. Med.156:454-465), both in the absence and in the presence of highly purifiedexogenous IL2 (10 U/ml final concentration).

IL2 Purification and Assay for IL2 Activity. We used highly purifiedIL2, prepared as previously described above [Welte, K, et al. (1982)Supra). This IL2 preparation is 37,000-fold enriched from lymphocyteconditioned medium, shows a specific activity of 10⁶ U/mg of protein,and consists of two active bands, on a silver-stained sodium dodecylsulfate-polyacrylamide gel [Welte, K, et al. (1982) Supra].

The IL2 assay was used as described before [Venuta, S, et al. (1982),UCLA Symposia in Molecular and Cellular Biology Supra; Gillis, S, et al.(1977) Nature (London) 268:154-156; Gillis, S, et al. (1978) J. Immunol.120:2027-203] using murine CTLL cells grown in the presence of log₂dilutions of putative IL2-containing media. The IL2 concentration ineach sample was calculated by probit analysis using a standardcontaining 2 U of rat IL2 [Gillis, S, et al. (1978) Supra).

One unit of IL2 was defined as the quantity of IL2 released in a 48-hrculture medium conditioned by rat spleen cells (1×10⁶ /ml) stimulated byconcanavalin A [5 micrograms/ml [Gillis, S, et al. (1978), Supra)]].Statistical analysis of the data presented was performed using thenonparametric Kruskal-Wallis test [Kruskal, WH, et al., J. Am. Stat.Assoc. 48:583 (1952); 48:907 (1953)], Spearman rank-correlationcoefficient [Siegel, S, (1956), Nonparametric statistics for theBehavioral Sciences HF Harlow (ed) New York, McGraw-Hill pp. 202-213],and Kaplan-Meyer calculations (Peto, R, et al. (1977) Br. J. Cancer35:1-39).

                                      TABLE IX                                    __________________________________________________________________________    Viral Studies Cell Surface Markers, and Survival.sup.a                                 Age                                                                  Diagnosis                                                                              (years)                                                                            Herpes group titers                                                                           ERFC.sup.b                                                                          OKT3 OKT4 OKT8                                                                              OKT4/OKT8                                                                             Survival.sup.c      __________________________________________________________________________    Kaposi's sarcoma                                                              1   LW   38   CMV:.sup.d                                                                        CF: anticomplementary                                                                     78.0  40.2 11.1 24.9                                                                              0.44    6.sup.+             2   CM   43   CMV:                                                                              IgG: 1/1024 77.5  49.6 15.4 26.1                                                                              0.59    6.sup.+                           EBV:.sup.e                                                                        1/320                                                       3   AB   38   CMV:                                                                              CF: 1/64    55.0  30.3 12.1 31.6                                                                              0.38    4.sup.                                IgG: 1/256                                                                EMV:                                                                              1/640                                                       4   JS   34   CMV:                                                                              CF: 1/128   33.0   40.5.sup.f                                                                         22.6.sup.f                                                                         13.4.sup.f                                                                       1.82    1.sup.                                IgG: >1/1024                                                              EBV:                                                                              1/640                                                       5   JP   36   CMV:                                                                              CF: 1/64    ND     84.0.sup.f                                                                         33.8.sup.f                                                                         49.1.sup.f                                                                       0.68    6.5.sup.+                         EBV:                                                                              1/2650                                                      6   DV   49   CMV:                                                                              CF: 1/64    81.0  17.9 33.6 36.5                                                                              0.92    5.sup.+                               IgG: >1/1024                                                              EBV:                                                                              1/320                                                       7   RS   36   CMV:                                                                              CF: 1/32    81.0  40.3 33.3 15.6                                                                              2.13    6.sup.+                               IgG: 1/128                                                                EBV:                                                                              1/5128                                                      8   GR   35   CMV:                                                                              CF: 1/32    53.0  39.9  6.5 26.8                                                                              0.24    3.sup.+                               IgG: >1/1024                                                              EBV:                                                                              1/2540                                                      9   KH   46   CMV:                                                                              CF: 1/32    78.0  29.5 39.3 32.9                                                                              1.19    2.sup.+                           EBV:                                                                              1/640                                                       10  EF   44   EBV:                                                                              1/40960     ND    55.1 27.4 38.4                                                                              0.71    2.sup.+             11  JP   48   CMV:                                                                              CF: 1/256   77.5  35.2 47.3 50.2                                                                              0.94    1.sup.                                IgG: >1/1024                                                12  MM   36   CMV:                                                                              CF: 1/128   62.5  24.5 13.6 17.2                                                                              0.79    2.sup.+                               IgG: 1/1024                                                 b                                                                             Opportunistic                                                                 infections.sup.g                                                              1   JC   24   CMV:                                                                              CF: 1/16    ND    ND   ND   ND  --      1.sup.                            EBV:                                                                              1/640                                                       2   JS   35   CMV:                                                                              CF: 1/64    72.0  26.0 30.0 61.0                                                                              0.49    1.sup.                            EBV:                                                                              1/320                                                       3   HC   37   CMV:                                                                              CF: 1/128   77.0  36.6  6.6 38.9                                                                              0.17    2.sup.+                           EBV:                                                                              1/1280                                                      4   JS   40   CMV:                                                                              IgG: 1/1204 ND    35.8  8.9 31.3                                                                              0.28    2.sup.+                           EBV:                                                                              1/320                                                       5   GL   24   CMV:                                                                              IgG: 1/1024 83.0  20.5 14.6 25.2                                                                              0.58    5.sup.+                           EBV:                                                                              1/320                                                       Reactive                                                                      lymphadenopathy                                                               1   CL   37   CMV:                                                                              CF: 1/64    ND    ND   ND   0   --      1.5.sup.+                         EBV:                                                                              1/2560                                                      2   CJ   40   CMV:                                                                              IgG: 1/512  58.0   42.0.sup.f                                                                         11.7.sup.f                                                                         30.0.sup.f                                                                       0.39    2.sup.+                           EBV:                                                                              1/1280                                                      3   JG   42   CMV:                                                                              IgG: 1/512  75.5  20.4 11.4  7.3                                                                              1.59    2.sup.+                           EBV:                                                                              1/320                                                       4   JP   27   CMV:                                                                              CF: 1/32    ND    ND   ND   ND  --      6.sup.+                           EBV:                                                                              1/2360                                                      __________________________________________________________________________     .sup.a Normal values for laboratory: ERFC, 80 ± 8%; OKT3, 67.7 ±        10.4; OKT4, 45.2 ± 8.6; OKT8, 24.8 ± 4.1; OKT4/OKT8 ratio, 1.83 .+-     0.27.                                                                         .sup.b ERFC, sheep erythrocyte rosetteforming cells.                          .sup. c Survival measured from the time of assay, (+) ongoing survival.       .sup.d CMV, cytomegalovirus, CMV IgG, determined by ELISA.                    .sup.e EBV, EbsteinBarr virus; EBV antibody titers measured by indirect       fluorescence (against viral capsid antigen).                                  .sup.f Leu series of monoclonal antibodies used.                              .sup.g Opportunistic infections present in this group: with Pneumocystis      carinii, CMV, ulcerative herpes simplex, Candida.                        

T-Cell Mitogen-Stimulated Proliferation

The proliferation of peripheral blood mononuclear cells stimulated byPHA, OKT3, or Pan T2 was measured on day 3 or incubation, since maximalproliferation was always noted to peak on this day, with patients andcontrols showing the same kinetics. The kinetics of IL2 productionshowed maximum levels of IL2 at 15-16 hr from the initiation of culturesin both patients and controls. Tables X shows the proliferative responseof the stimulated cells in the absence and presence of exogenous hp IL2.All patients with KS and opportunistic infections had significantlylower mitogen-stimulated DNA synthesis as compared to the controls,irrespective of the mitogen used (P less than 0.01). The patients withlymphadenopathy exhibited significantly lower responses only in the OKT3assay as compared to the normals (P=0.009). All but two patients (No. 9with KS and No. 4 with lymphadenopathy) exhibited a very lowproliferative response to OKT3 (maximum cpm, less than 30,000). It isalso noted that nine patients (five with KS and four with opportunisticinfections) had a very low proliferative response to PHA (maximum cpm,less than 18,000). This markedly reduced proliferative response wasparalleled by a consistently low response in the Pan T2-stimulatedcultures of eight (four with KS and four with opportunistic infections)of those nine patients who failed to respond to PHA (maximum cpm, lessthan 4000). The other patients with intermediate proliferation inresponse to PHA also showed higher proliferation in the Pan T2 assay.There were no significant differences among the patient groups (KSversus the lymphadenopathy or opportunistic infection group,lymphadenopathy versus the opportunistic infection group) with respectto radioactive thymidine incorporation in any of the mitogen-stimulatedPBL proliferation of patients with lymphadenopathy was significantlyhigher than that of patients with opportunistic infections (P=0.027). Intwo KS patients (Nos. 1 and 3) we repeated the assays after 4.5 and 4months, respectively. PBL of patient No. 1, who had progressive disease,incorporated 9500 cpm in respose to PHA the second time versus 54,800cpm in the first study, 6500 cpm versus 18,000 cpm in the OKT3 assay,and 2000 cpm versus 38,000 cpm in the Pan T2 assay. Patient No. 3, inwhom the repeated assay was run 48 hr prior to his death, showed nosignificant response to any of the three mitogen studies, while he hadshown a low but definite mitogen response when tested the first timewith 1600 cpm in the PHA proliferation, 3500 cpm in the OKT3proliferation, and 2400 cpm in the PAN T2 proliferation. Although thelongest follow-up time from the performance of assays did not exceed 6.5months, the level of OKT3-induced proliferation correlated withpatients' survival (Kaplan-Meyer calculations). All 10 patients withOKT3-induced proliferation greater than 13,000 cpm were alive at lastfollow-up (range 1+ to 6.5⁺ months), whereas 5 of 11 patients withOKT3-induced proliferation less than 13,000 cpm had died (P=0.015) TableX).

                                      TABLE X                                     __________________________________________________________________________    Mitogen Induced Proliferation as Measured by [.sup.3 H]Thymidine Uptake       (cpm × 10.sup.3) With And                                               Without the Addition of Purified IL2.sup.a                                                 PHA (cpm × 10.sup.3)                                                                OKT3 (cpm × 10.sup.3)                                                               Pan T2 (cpm × 10.sup.3)            Diagnosis    -IL2  +IL2  -IL2  +IL2  -IL2  +IL2                               __________________________________________________________________________    Kaposi's sarcoma                                                              1.    LW     54.8  55.6  18.0  43.5  38.0* 71.5                               2.    CM     7.9   21.8  11.0  46.4.sup.c                                                                          0.5   17.5                               3.    AB     1.6   14.5  3.5   14.6  2.4   17.6                               4.    JS     6.6   50.6  12.8  37.2  13.7  68.7.sup.c                         5.    JP     72.2* 108.5 19.3  50.7.sup.c                                                                          50.7* 82.0                               6.    DV     13.2  21.0  10.3  27.2  0.8   9.9                                7.    RS     56.4  69.5  29.1  80.3.sup.c                                                                          35.0  78.1                               8.    GR     17.4  26.4  12.9  16.9  19.2  17.5.sup.n                         9.    KH     29.7  28.0.sup.n                                                                          31.6  50.1.sup.c                                                                          17.3  44.4.sup.c                         10.   EF     25.2  27.6.sup.n                                                                          15.9  41.2  18.1  46.9.sup.c                         11.   JP     20.5  22.6.sup.n                                                                          12.7  31.3  5.7   23.7                               12.   MM     54.3  54.3  7.2   13.0  0.6   0.7.sup.n                          Opportunistic infections                                                      1.    JC     28.9  28.7.sup.n                                                                          11.4  25.2  0.3   1.4.sup.n                          2.    JS     3.1   3.3.sup.n                                                                           3.2   1.7.sup.n                                                                           3.5   6.3                                3.    HC     10.3  24.5  8.4   22.0  18.7  37.7.sup.c                         4.    JS     16.0  26.0  14.7  33.3  0.4   0.9.sup.n                          5.    GL     11.4  25.7  14.4  30.1  1.5   4.9                                Reactive lymphadenopathy                                                      1.    CL     41.7  44.3  13.1  26.7  20.4  32.3.sup.c                         2.    CJ     55.0  53.0  27.8  42.0  19.4  36.5.sup.c                         3.    JG     26.0  29.4  12.7  25.9  0.5   1.4.sup.n                          4.    JP     108.6*                                                                              137.0 48.2  86.2  72.6* 112.5                              Heterosexual controls                                                                      78.9  93.3  66.1  84.0  60.2  91.2                               [median (range)]                                                                           (56.5-110.9)                                                                        (59.1-125.0)                                                                        (46.3-88.3)                                                                         (55.9-127.0)                                                                        (27.6-88.0)                                                                         (41.0-126.0)                       N = 10                                                                        __________________________________________________________________________     .sup.a *,cpm within normal range before the addition of IL2 (The values       for patients 1,7 and 12 with Kaposi's sarcoma and 2 with lymphadenopathy      in the PHA assay without purified IL2 considered biologically normal.)        With the addition of IL2:                                                     .sup.c complete correction;                                                   .sup.n no response.                                                      

                                      TABLE XI                                    __________________________________________________________________________    IL2 Production by PBL in Response to Stimulation with PHA, OKT3, and Pan      T2                                                                                          N.sup.a                                                                         PHA    OKT3   Pan T2                                          Diagnosis     [IL2 (U/ml); median (range)]                                    __________________________________________________________________________    Kaposi's sarcoma                                                                            12                                                                              1.1(<0.1-4.2)                                                                        0.9(0.2-1.8)                                                                         0.3(<0.1-1.3)                                   P value.sup.b   0.020  0.002  0.024                                           Opportunistic infections                                                                     5                                                                              0.2(<0.1-0.9)                                                                        0.2(<0.1-1.4)                                                                        0.1(<0.1-0.7)                                   P value         0.006  0.006  0.050                                           Reactive lymphadenopathy                                                                     4                                                                              1.1(0.6-1.6)                                                                         0.6(0.5-9.6)                                                                         0.2(<0.1-0.6)                                   P value         >0.05  >0.05  0.030                                           Heterosexual controls                                                                       10                                                                              2.3(0.8-6.8)                                                                         3.5(0.9-16)                                                                          0.7(0.4-2.4)                                    __________________________________________________________________________     .sup.a N number of patients                                                   .sup.b P value based on the KruskalWallis test comparing patient groups       with controls in each mitogeninduced assay.                              

                                      TABLE XII                                   __________________________________________________________________________    Simulation of the Proliferative Response of PBL to                            PHA, OKT3, and Pan T2 by the Addition of IL2                                                N.sup.a                                                                         PHA    OKT3   Pan T2                                          Diagnosis     [cpm(+IL2)/cpm(-IL2).sup.b ; median (range)]                    __________________________________________________________________________    Kaposi's sarcoma                                                                            12                                                                              1.4(0.9-9.1)                                                                         2.6(1.3-4.2)                                                                         2.6(0.9-35.7)                                                          P = 0.000*                                             Opportunistic infections                                                                     5                                                                              1.6(1.0-2.4)                                                                         2.2(0.9-2.1)                                                                         2.0(1.8-3.8)                                    Reactive lymphadenopathy                                                                     4                                                                              1.1(0.9-1.3)                                                                         1.9(1.5-2.0)                                                                         1.7(1.5-2.7)                                                           P = 0.006*                                             Heterosexual controls                                                                       10                                                                              1.1(0.9-1.4)                                                                         1.3(1.1-1-5)                                                                         1.6(1.1-2.9)                                    __________________________________________________________________________     .sup.a N number of patients                                                   .sup.b cpm (+IL2)/cpm(-IL2) = [.sup.3 H]thymidine incorporation in the        presence of added IL2 divided by [.sup.3 H]thymidine incorporation withou     the addition of IL2.                                                          *Ratio of cpm (+IL2)/cpm(-IL2)significantly higher than in controls using     the KruskalWallis test. All other IL2induced increments of Tcell              proliferation were not significant at the 0.05 level compared to controls                                                                              

The OKT4⁺ /OKT8⁺ Ratio

The patient group had significantly lower OKT4⁺ /OKT8⁺ ratios comparedto controls (P=0.030), with a median ratio of 0.79 versus 1.88 forcontrols. There was no significant difference with respect to OKT4⁺/OKT8⁺ ratio among patient groups (KS versus the lymphadenopathy oropportunistic infection group, lymphadenopathy versus the opportunisticinfection group). There was no correlation between the level ofproliferation induced with any of the mitogens used and the OKT4⁺ /OKT8⁺ratio, as well as no correlation between patients' survival and thisratio (P greater than 0.05).

Endogenous IL2 Production

Patients with KS and opportunistic infections produced significantlylower amounts of IL2 than normal controls irrespective of the mitogenused (Table XIV). The median IL2 production in the OKT3-stimulatedcultures was 0.9 U/ml for KS patients and 0.2 U/ml for patients withopportunistic infections, compared to 3.5 U/ml for normal controls.Patients with lymphadenopathy produced significantly lower amounts ofIL2 only in the Pan T2-stimulated cultures, while IL2 production was notsignificantly lowered in this patient group when OKT3 or PHA was used asmitogen (P greater than 0.5). The amount of IL2 produced by cultured PBLcorrelated significantly with the level of proliferation (absolute cpm)in all mitogen-stimulated assays for both patients and controls (P lessthan 0.01) using the Spearman rank-correlation coefficient).

                  TABLE XIII                                                      ______________________________________                                        OKT3 AND PHA INDUCED IL2 PRODUCTION OF                                        PBMC FROM PATIENTS AFTER BMT                                                                     OKT3                                                                          (1.25 ng/ml) PHA (0.5%, v/v)                                                  IL2 (U/ml)   IL2 (U/ml)                                    Diagnosis    n     median (range)                                                                             median (range)                                ______________________________________                                        Leukemia     12    <0.2(<0.2-1.5)                                                                             <0.2(<0.2-1.0)                                (ALL, AML, CML)                                                               Aplastic anemia                                                                            6     0.25(<0.2-1.0)                                                                             <0.2(all<0.2)                                 Severe combined                                                                            2     <0.2(both<0.2)                                                                             <0.2(both<0.2)                                immunodeficiency                                                              Autologous BMT                                                                             3     <0.2(all<0.2)                                                                              <0.2(all<0.2)                                 (NHL, neuroblastoma)                                                          Controls                                                                      (a)normal    21    3.5(0.9-16)  2.3(0.8-6.8)                                  (b)prior BMT*                                                                              8     1.5(0.4-2.5) 1.0(0.7-1.6)                                  ______________________________________                                         *patients prior to BMT (all diagnostic subgroups)                        

Effect of Highly Purified IL2 on Mitogen-Induced Proliferation

The addition of hp IL2 in the absence of mitogenic stimulation did nothave any effect on the proliferation of PBL from patients or controls.In the KS group, hp IL2 brought the level of thymidine incorporationwithin the normal range of patients 2, 5, 7, and 9 with OKT3 as mitogenand normalized the proliferation for patients 4, 9, and 10 with Pan T2as mitogen. hp IL2 with Pan T2 as mitogen also normalized theproliferation of patients 1 and 2 in the lymphadenopathy group and ofpatient 3 in the opportunistic infection group (Table XII). hp IL2 wasunable to induce complete correction for any patient in thePHA-stimulated assay.

In several patients there was no significant correction of proliferation(less than 25% increment) with the addition of hp IL2 (Table X). Thesenonresponder patients in the PHA assay were three patients with KS (Nos.9, 10, and 11) and two patients with opportunistic infections (Nos. 1and 2); in the OKT3 assay, only one patient (No. 2) with opportunisticinfection; and in the Pan T2 assay, two patients with KS (Nos. 8 and12), one patient with lymphadenopathy (No. 3), and two patients withopportunistic infections (Nos. 1 and 4) (Table X). The median increasein [³ H] thymydine incorporation after the addition of IL2 was 1.4-,1.1-, and 1.6-fold, respectively, for KS, lymphadenopathy, andopportunistic infection patients in PHA-stimulated culture; 2.6-, 1.9-,and 2.20 fold, respectively, after OKT3 stimulation, and 2.6-, 1.7-, and2.0-fold, respectively, in the Pan T-2-stimulated cultures. Patientswith KS and lymphadenopathy, compared to controls, showed significantlyhigher increments of T-cell proliferation in response to exogeneous IL2when OKT3 was used as mitogen (P less than 0.01 Table XI).

IL is a potent regulator of T cell proliferation, acting as an antigennonspecific, genetically unrestricted mediator [Watson, J, et al.(1980), Immunol. Rev. 51:257-278; Smith, KA, (1980), Immunol. Rev.51:337-357). Previously, the OKT4⁺ helper subset of T cells was thoughtto be solely responsible for the synthesis of IL2 upon appropriateantigen or mitogen stimulation and interaction with macrophages andtheir products (Palacios, R, et al. (1981), Cell Immunol. 63:143-153).Recent data proved, however, that IL2 can be secreted by OKT8⁺lymphocytes as well [Meuer, SC, et al., (1982) J. Immunol.129:1076-1079; Luger, TA, et al. (1982), J. Clin. Invest. 70:470-473].Antigens or mitogens such as PHA or the monoclonal antibodies OKT3 andPan T2 are required to activate IL2 responder T cells to express the IL2receptor, which appears essential for IL2 binding and subsequenttriggering of T-cell proliferation [Ruscetti, FW, et al. (1981), Blood57:379-394; Smith, KA, (1980), Immunol. Rev. 51:337-357; Palacios, R, etal. (1981), Cell Immunol. 63:143-153).

In the present study we have investigated the ability of PBL fromhomosexual patients with KS, lymphadenopathy, and opportunisticinfections to generate IL2 and to proliferate upon stimulation in vitrowith PHA and two mitogenic monoclonal antibodies, as well as the effectof exogenous highly purified IL2 on the proliferative response inducedby these mitogens. We studied IL2 production and response in thesehomosexuals with KS and opportunistic infections since this patientspopulation has been shown to have a rather unique immunodeficiencysyndrome [Siegal, FP, et al. (1981) Supra; Gottlieb, MS et al. (1981)Supra; Koziner, B, et al. (1982), N. Engl. J. Med. 306:933-934) ofunknown etiology and pathogenesis, and no treatment has so far been ableto restore their immmune functions to normal either in vitro or in vivo.The homosexuals with reactive lymphadenopathy were included in the studysince they might represent the first step toward the clinicallymanifested acquired immunodeficiency.

To our knowledge there is only one report in the medical literaturedealing with the aspects of IL2 synthesis and its role in theproliferative response to PHA in patients with primaryimmunodeficiencies (Lopez-Botet, M, et al. (1982), J. Immunol.128:679-683). We found that the addition of IL2-containing supernatantto cultured PBL from patients with primary immunodeficiencies caused anincrease in DNA synthesis in the presence of suboptimal concentrationsof PHA. The PBL of these patients with a reduced proliferative responseto PHA ("hyporesponders") were shown to produce significantly loweramounts of IL2 [Lopez-Botet, M, et al. 1982 Supra]. We have describedpreviously the ability of exogenous IL2 to increase thymidineincorporation by PBL cultures of normal controls when stimulated withPHA [Mertelsmann, R, et al. (1981) Blut 43:99-103], although this wasnot seen by Lopez-Botet et al. (Lopez-Botet, et al. (1982) Supra). As asource of IL2 these authors used only IL-2 containing conditioned media,whereas our IL2 preparation derived from normal human lymphocytes washighly purified, nonmitogenic, and free of other lymphokine activities[without alpha-or gamma-interferon, granulocyte macrophage colonystimulating factor, T-cell replacing factor, B-cell groweth factor,T-cell replacing factor, B-cell growth factor, thymocyte differentiatingactivities [Welte, K, et al. (1982), J. Exp. Med. 156:454-464]], whichmight account for the discrepancy. Although the absolute increase inproliferation after the addition of hp IL2 was similar in patients andcontrols, the median values of IL2-induced increments were higher foreach patient groups compared to the controls (median value equal to thecontrols only the lymphadenopathy group, PHA assay). The relativeincrements were statistically significantly higher at P less than 0.01for the KS and the reactive lymphadenopathy groups in the OKT3 assay.

We have shown that PBL from all homosexual patients investigated by us,except for patient No. 4 from the lymphadenopathy group, failed to showa normal proliferative response to OKT3. This defect appears to be dueto a decrease in IL2 production, since PBL from KS and patients withopportunistic infections produced only low quantitites of IL2. hp IL2 inthe OKT3-stimulated cultures was able to normalize the proliferaion offour patients with KS and to partially restore the proliferation inanother 15 deficient patients, except patient No. 2 from theopportunistic infections group. We have also studied the response of PBLfrom the patients to an additional mitogenic monoclonal antibody, PanT2, isolated in this laboratory. This antibody appears to recognize adifferent epitope of the same molecular complex recognized by OKT3,which appears to play an important role in T-cell activation (Wang, CY,et al. (1983) (submitted for publication). In the presence of Pan T2,the addition of IL2 normalized the proliferative response in sixpatients and partially corrected the response in another six patients.The Pan T2-induced proliferation was onto correctable with IL2 in fivepatients. Pan T2 proved to be the most sensitive of the three mitogensin detecting an IL2 production abnormality, since using Pan T2, weobserved significantly lower amounts of IL2 even in the lymphadenopathygroup. The results indicate that all groups of patients have a defect inIL2 production. The defect does not appear to be at the level of the IL2receptor, since all mitogens tested were able to induce a proliferativeresponse in the presence of exogenous IL2. The difference between theIL2 responder cells in normal heterosexual controls and those inhomosexual patients appears thus to be more of a quantitative than aqualitative nature and possibly related to the different absolute countsof OKT4⁺ and OKT8⁺ subsets.

Our data are consistent with the previously reported decreased T-helpersubpopulation (OKT4⁺) in these patients [Gottlieb, MS, et al. (1981),Supra; Koziner, B, et al. (1982) Supra]. The decreased OKT4⁺ /OKT8⁺ratio (helper/suppressor) previously reported (Koziner, B, et al. (1982)Supra) and also found in our patient population suggests either that theproduction of IL2 by OKT8⁺ T cells in homosexuals is less than that ofOKT4⁺ cells or, alternatively, that the OKT8⁺ subset might absorb andrequired higher concentrations of IL2 for the induction of proliferationthan OKT4⁺ cells. In healthy blood donors similar concentrations of IL2were found in supernatants from mitogen-stimulated cultures of highlyenriched OKT4⁺ or OKT8⁺ cells [Meuer, SC, et al. (1982) J. Immunol.129:1076-1079].

Kornfield et al. recently reported a significantly lower OKT4⁺ /OKT8⁺ratio in symptomatic homosexuals (lymphadenopathy and/or opportunisticinfections) compared to asymptomatic homosexuals [Kornfeld, H, et al.(1982) N. Engl. J. Med. 307:729-731]. We were unable to find acorrelation between OKT4⁺ /OKT8⁺ ratio and PBL proliferative ability ofIL2 production under mitogen stimulation.

It may be only homosexual patients with inverted OKT4⁺ /OKT8⁺ ratios aredeficient in IL2 production; other pathological entities associated withinverted helper/suppressor ratio may well show the same IL2 productiondefect. Since advanced age has previously been shown to be associatedwith decreased IL2 production [Gillis, S, et al. (1981) J. Clin. Invest.67:937-042], the classic KS seen in the older population may also berelated to a similar immune defect, as seen in the young homosexualmales. It will be of interest to observe the further course of thedisease(s) in the "healthy" homosexuals with lymphadenopathy, since thisgroup appears to have immune alteration as evidence by a lower responsein the OKT3-stimulated cultures.

Follow-up assays in the same patients seem to have a prognostic value,as suggested by the two patients who had repeated determinations oftheir PBL proliferative capacity.

The level of OKT3-induced proliferation may also be of prognosticsignificance (P=0.015), as suggested by our data, but longer follow-upis necessary to document the validity of this observation. It is ofinterest to note that of the five patients that died within the6.5-month follow-up, three were nonresponders in at least one of theIL2-supplemented mitogen assays.

Our data indicate that the proliferation defect can be corrected atleast partially by the addition of IL2. However, the patients' T cellsdo not spontaneously express receptors for IL2 since they need to beprimed with a mitogen before they become responsive to IL2.

The in vivo administration of IL2 may be beneficial for homosexualpatients with and without KS who are severely immunocompromised. WhetherIL2 receptor activation by the simultaneous administration of mitogenicmonoclonal antibodies is required for the restoration of the immuneresponse in vivo remains to be determined. A phase I trial of IL2 inthis pateint population has been initiated.

Phase I/Phase II Clinical Trial: As of 5/1/83 a total of twelve patientshave received hp IL2 as part of the phase I/phase II trial of hpIL2. Themode of administration, dosage schedules and monitoring are detailedabove. So far a dose level of 20,000 U/m² daily for 14 days has beenreached. We have not seen any evidence of toxicity either by clinicalevaluation or by monitoring laboratory studies. Furthermore, preliminaryevidence suggests biological activity of hpIL2 in man in vivo, withimprovement of some of the marker studies while on hpIL2. Preliminaryevidence for efficacy was also seen with an apparent effect of IL2 ondisease related symptoms, e.g., reduction of fever in patients withAIDS. Although the evidence for biological activity and clinicalefficacy is very preliminary at this point, we are encourage by theabsence of side-effects of hpIL2 and the first indications of an in vivoeffect in man. The current trail will be continued until either toxicityis reached or a dose level resulting in definite and reproduciblebiological activity can be established. Murine studies investigatingdifferent dose levels and schedules in transplanted and autochthonoustumor models will be performed in parallel with the ongoing phase Itrial.

Use of hp IL2 in transplantation disorders

Using OKT3monoclonal antibody as a mitogen, we have studied Interleukin2 (IL2) production and proliferation in peripheral blood mononuclearcells (PBMC) of 23 patients receiving bone marrow transplants. Twentypatients were recipients of allogeneic bone marrow for treatment ofhematological malignancies, a plastic anemias (AA) or severe combinedimmunodeficiences (SCID). Three patients with Hodgkin's disease orneuroblastoma received autolgous bone marrow. Endogeneous IL2 productionwas not detectable (less than 0.2 U/ml) in PBMC of 18 patients and wasvery low in PBMC from 5 patients (0.5-1.5 U/ml) as compared to normalcontrols (median 3.5 U/ml) or pretransplant patients (median: 1.5 U/ml).The low IL2 production was associated with defective OKT3 inducedproliferation of PBMC in 19 of 23 patients studied. In the first 6months after BMT, 14 of 15 patients (93%) showed defective proliferationof PBMC as compared to 5 of 8 patients (63%) tested between 7 and 18months after BMT (p less than 0.1). In all but three patients, additionof highly purified human lymphocyte IL2 (hp IL2) restored OKT3 inducedproliferation of PBMC to within the normal range. This studydemonstrates that PBMC in patients after BMT have a defect of IL2production but are able to express IL2 receptors in response to OKT3antibody and to proliferate normally upon addition of hpIL2.

PBMC of all patients showed similar functional defects whether or notthey received additional therapy, including various conditioningregimens prior to BMT and immunosuppressive therapy after BMT. Theseobservations suggest that T cell defects after BMT are most likelysecondary to quantitative or qualitative defects of transplanted Tlymphocytes or their precursors.

During the first two years after transplantation recipients ofallogeneic marrow transplants demonstrate a severe deficiency ofcellular and humoral immunity [Noel, D. R., et al. (1978) Blood 51:1087; deBruin, H. G., et al. (1981) J. Immunol. 127: 244; Witherspoon,R. P., et al. (1982) Blood 59: 844; Friedrich, W., et al. (1982) Blood59: 696; Fox, R., et al. (1982) Blood 60: 578; Donnenberg, A. D., et al.(1982) J. Immunol. 129: 1080; Schroff, R. W., et al. (1982) J. Immunol.129: 1926; Mori, T., et al. (1983) J. Immunol. 130: 712]. Thisimmunodeficiency leads to increase susceptibility to frequently lethalbacterial, fungal, and viral infections.

Interleukin 2 (IL2) is one of the major cytokines responsible for clonalexpansion of T cells [Ruscetti, F. W., et al. (1981) Blood 57: 379] andhuman natural killer (NK) cells [Domzig, W., et al. (1983) J. Immunol.130: 1970; Flomenberg, N., et al. (1983) J. Immunol. 130: 2635] as wellas for the activation of cytotoxic effector cells [Domzig, W., et al.Supra (1983); Merluzzi, V. J., et al. (1983) J. Immunol. 131: 806]. Therole of IL2 in several immunodeficiency states [Welte, K., et al. (1983)in "Modern Trends in Human Leukemia V" Springer Verlag, Berlin-New Yorkpp. 369; Ciobanu, N., et al. (1983) J. Clin. Immunology 3: 332;Flomenberg, N., et al. (1983) J. Immunol. 130: 2644] as well as incertain lymphoid leukemias [Gootenberg, J. E., et al. (1981) J. Exp.Med. 154: 1403; Venuta, S., et al. (1983) Blood 61: 781] has beenpreviously documented. Defective IL2 production could be one possiblemechanism for the abnormal immune function in patients after bone marrowtransplantation (BMT) [Donnenberg, A. D., et al. (1982) J. Immunol. 129:1080; Mor, T., et al. (1983) J. Immunol. 130: 712].

Recently, OKT3, a monoclonal antibody against a T-cell surface antigenhas been shown to be mitogenic even in nanogram concentrations [VanWauwe, J. P., (1980) J. Immunol. 124: 2708; Chang, T. W., et al. (1981)Proc. Nat'l. Acad. Sci. USA 78: 1805] and to induce IL2 productin intotal T cells as well as in T cell subsets [Welte, K., et al. (1983) J.Immunol. 131: 2356]. OKT3 appears to recognize an epitope of theantigen-recognition complex on T-lymphocytes [Chang, T. W., et al.(1981) Proc. Nat'l. Acad. Sci. USA 78: 1805; Reinherz, E. L., et al.(1982) Cell 30: 735] triggering mitogenesis in a way similar to thatinduced by antigen.

We studied IL2 production and response of peripheral blood mononuclearcells (PBMC) from patients up to 18 months after BMT using OKT3 antibodyas mitogen and, as control, phytohemagglutinin (PHA). In addition weinvestigated whether highly purified human lymphocyte IL2 (hpIL2)[Welte, K., et al. (1982) J. Exp. Med. 156: 454] was capable ofrestoring defective proliferative responses of T cells in vitro.

Patients: The study group consisted of 20 recipients of an allogeneicBMT: 4 patients with acute myelogenous leukemia (AML) in first or secondremission, 4 patients with acute lymphoblastic leukemia (ALL) in secondor third remission, 4 patients with chronic myelogeneous leukemia (CML),6 patients with aplastic anemia (AA), and 2 patients with severecombined immunodeficiency (SCID). In addition 3 recipients of autologousBMT were studied: 1 patient with nuroblastoma and 2 patients withNon-Hogkin's lymphoma (NHL). Details of the transplantation procedureshave been described [Friedrich, W., et al. (1982) Blood 59: 696].Patients with AML ALL and CML were conditioned for transplantation withcyclophosphamide (60 mg/kg for 2 days) and hyperfractionated total bodyirradiation (TBI, total dose 1320 rads). In the aplastic anemia group, 4patients received only preparative chemotherapy with cyclophosphamide(50 mg/kg for 4 days), cytosine arabinoside (200 mg/kg/day for 5 days)and 6-thioguanine (200 mg/kg/day for 5 days), whereas 2 other patientswere conditioned similar to patients with leukemias but with less TBI(800,300 rads, respectively). SCID patients received no cytoreductivetreatment. The patient with neuroblastoma was treated withL-phenylalanine mustard (L-PAM) 240 mg/m² plus dihydroglactitol 240mg/m² and low TBI, while the two patients with NHL received the sameregimen used for the patients with leukemias. All patients receiving anallogeneic BMT except one, received the marrow from HLA-A,B,C, and Didentical siblings and engrafted permanently following the firstattempt. One patient with SCID engrafted permanently only after thefourth attempt, when receiving a lectin separated marrow from hishaploidentical mother. Post-transplant immune suppression for allpatients receiving allogeneic BMT consisted of methotrexate 15 mg/m² onday 1, followed by 10 mg/m.sup. 2 on days 3,6,13,20 and weeklythereafter to day 100. All immune suppressive drugs were stopped at thattime. Patients with graft- versus-host disease (GvHD) of at least grade2 were treated with high dose prednisone (2 mg/kg/d). One AML patientreceived prednisone plus cyclosporine A (10 mg/kg/d) while another ALLpatient was maintained only on azathioprine (50 mg/d). At the time ofthe IL2 analysis, 13 patients had GvHD (4 patients grade 1; 3 patientsgrade 2; and 6 patients grade 3). Four of the 13 patients had acuteGvHD.

Proliferation Assay: Mononuclear cells (PBMC) from 10-20 ml ofheparinized blood were separated by density gradient centrifugation onFicoll-Hypaque as previously described (Welte, K., et al. (1983) J.Immunol. 131: 2356) and resuspended at a final concentration of 10⁶cells/ml in RPMI 1640 supplemented with 10% heat-inactivated FCS,glutamine (2 mM), Penicillin (50 U/ml), and Streptomycin (50 microg/ml).Each sample was stimulated in triplicate microwell cultures (#3596culture plate, Costar Inc. Cambridge, MA) in the presence or absence ofmitogen (PHA, OKT3), and in the presence or absence of hpIL2 [Welte, K.,et al. (1982) J. Exp. Med. 156: 454]. Unless stated otherwise theconcentrations used were 1.25 ng/ml for OKT3 Ortho Pharmaceuticals,Raritan, NJ) and 0.5% (v/v) for PHA (PHA-M, Grand Island BiologicalCo.). After 24 hours, 100 microl supernatant were removed from each wellto be assayed for IL2 activity. Identical cutlures were incubated for 3days and then pulsed for 4 hrs. with ³ H-thymidine (0.5 micro Ci/well;New England Nuclear, Boston, MA) and the ³ H-thymidine uptake measuredas described previously [Welte, K., et al. (1983) Springer Verlag,Berlin-New York pp. 369 Supra; Welte, K., et al. (1983) J. Immunol. 131:2356]. Maximum IL2 production was seen at 24 hours while maximumproliferation was seen after 3 days. Interleukin 1 (IL1) was purchasedfrom Genzyme, Co. (Norwalk, Conn.) and its effect on IL2 production andlymphocyte proliferation was tested in PBMC cultures from two patients.Statistical evaluation was performed using the Kruskal-Wallis test(two-side p values).

For the IL2 assay, IL2 dependent cultures of cytotoxic T lymphocyteswere used as previously described above. (Welte, K., et al. J. Exp. Med.Supra)

IL2 Production: Table XIV details the IL2 production data of the patientpopulation. PBMC from 18 patients after BMT did not produce detectableamounts of IL2(less than 0.2 units per ml). BPMC from 5 patientsproduced between 0.5 and 1.5 U/ml IL2 as compared to a median of 3.5U/ml IL2 in controls (n=21) (p less than 0.001), when stimulated withOKT3 antibody. IL2 production was not significantly different betweenthe different diagnostic subgroups (p less than 0.1). PBMC from 8patients (all diagnostic subgroups), analyzed prior to BMT, produced IL2in the low normal range (Table XII).

Proliferative Response to OKT3 Antibody and PHA: As shown in FIGS.10-12, low IL2 production was followed by a low proliferative responseof PBMC, as measured by ³ H-thymidine incorporation on day 3. PBMC from9 of the 12 patients with leukemias, 5 of 6 patients with AA, both SCIDpatients, and the 3 patients after autologous BMT had defective mitogenresponses to OKT3 (FIG. 10) as compared to normal controls (n=21). ThePBMC from 8 patients (all diagnostic subgroups) tested prior to BMTshowed a wide range of proliferative responses to OKT3 antibody (median:38,000 cpm, range 15,000-88,000 cpm), and to PHA (median: 71,000, range17,000-165,000 cpm), respectively. These responses were significantlyhigher than those seen after BMT (p less than 0.05). Whereas the medianproliferative response of PBMC from patients after BMT in the absence ofIL2 was similar for OKT3 and PHA as mitogens, the median ³ H-thymidineincorporation in the presence of hp IL2 was much higher, whenOKT3(median 50,500 cpm) rather than when PHA was used as mitogen (median24,500 cpm) FIG. 11. In all except 3 patients, proliferation of PBMCcould be restored to within the normal range by hpIL2, (FIGS. 10-12)when OKT3 was used as mitogen. The enhancement of proliferation byaddition of hpIL2 (10 U/ml) to OKT3 or PHA stimulated PBMC wassignificantly higher in patients (OKT3: median 6.8 fold; PHA: 3.4 fold)than in normal controls (OKT3: median 1.34 fold; PHA: 1.13 fold) (p lessthan 0.001). However, this enhancement was higher for OKT3 than for PHA(p less than 0.005); comprising enhancement ratios in patients vs.normal controls). To test whether defective production of IL1 bymonocytes was responsible for the low endogenous IL2 production andproliferative responses of PBMC from the BMT patients, IL1 (100 U/ml)was added to the mitogen stimulated cultures of two patients. No effectwas seen, both, in the absence and presence of exogenous IL2.

Studies in controls and 6 patients after BMT with OKT4/OKT8 T cellratios of less than 1.0 showed that the ratio of T lymphocyte subsetsdid not change in vitro when cultured for 3 days in the presence of OKT3antibody and hpIL2. This finding may suggest that there was nopreferential growth of one subpopulation of T cells under ourexperimental conditions.

The Effect of Time from BMT on Mitogen Responses to OKT3 Antibody: FIG.12 demonstrates that a proliferative defect was present even up to 18months after BMT. However, the median proliferation of PBMC in absenceof hpIL2 was higher (12,000 cpm) in the group 7-18 months after BMT thanin the group in the first 6 months after BMT (5800 cpm) (p=0.09). In thepresence of hpIL2, the median ³ H-thymidine uptake of PBMC was 79,000cpm in the 7-18 months group and 41,000 cpm in the group less than 7months after BMT (p=0.06).

The Effect of Conditioning Regimens on Mitogen Responses to OKT3Antibody: IL2 production and proliferation of PBMC from patientsreceiving no conditioning regimen (SCID), chemotherapy alone (4 patientswith AA) or receiving chemotherapy and TBI (1320 rad for patients withleukemia or receiving autologous transplant; 300 or 800 rad for twopatients with AA) were compared. No differences between these groupswere seen with respect to endogenous IL2 production or proliferativeresponses to OKT3 or PHA, respectively, in the absence or presence ofexogenous hpIL2.

The Effect of GvHD and Immunosuppressive Drugs on Mitogen Responses toOKT3 Antibody: The study population consisted of three groups withrespect to immunosuppressive medications given after BMT. Patientsreceiving autologous BMT were given no further immunosuppressive therapyafter BMT. All patients receiving allogeneic BMT, were treated withprophylactic methotrexate, while those with GvHD received, in addition,high dose prednisone (see above) Only one patient received prednisoneplus cyclosporine A for GvHD. No differences between groups were seenwith respect to endogenous IL2 production (Table XIV) and proliferativeresponses to OKT3 antibody and PHA, respectively, in the absence orpresence of exogenous IL2 (FIG. 10). It is interesting that PBMC fromthe one patient receiving cyclosporine A, showed that the lowest mitogenresponses of all patients tested (OKT3 response without IL2: 1,100 cpm,with exogenous hpIL2: 13,000 cpm).

The study group included 13 patients who developed acute or chronic GvHD(grade 1-3) (shown with asterisks besides the symbols in FIG. 1). Therewas no statistically significant differences in the mitogen responsesnor in the restoration of proliferation of PBMC by hpIL2 betweenpatients with or without GvHD.

This demonstrates, that PBMC from patients up to 18 months after BMThave defective mitogen responses which are secondary to a defect in IL2production. This finding is specific for patients after BMT, since PBMCfrom patients tested prior to BMT do not exhibit this defect to the samedegree. Addition of IL1 to mitogen stimulated PBMC cultures of twopatients was without effect on IL2 production suggesting that defectiveIL1 production by monocytes is not responsible for the observed defects.Most of the patients had an imbalance in the OKT4/OKT8 (Leu 3/Leu 2) Tcell ratio with a predominant OKT8+ subpopulation [deBruin H. G., et al.(1981) J. Immunol. 127: 244; Friedrich, W., et al. (1982) Blood 59: 696;Fox, R., et al. (1982) Blood 60: 578; Schroff, R. W., et al. (1982) J.Immunol. 129: 1926, own unpublished observations]. However, using OKT3as mitogen both subgroups (OKT4+, OKT8+) of T lymphocytes were capableof producing IL2 (Welte, K., et al. (1983) J. Immunol. 131: 2356). It istherefore unlikely that the reversed OKT4/OKT8 ratio is the reason forthe IL2 production defect. In addition, we have not found anycorrelation between IL2 production by PBMC and OKT4/OKT8 T cell ratio in10 patients tested. The lack of correlation between low OKT4/OKT8 T cellratios and OKT3 mitogen responses has recently been documented in otherimmunodeficiency states including patients with acquiredimmunodeficiency syndrome [AIDS; Welte, K., et al. (1983) Springer,Verlag, Berlin-New York pp. 369 Supra; Ciobanu, N., et al. (1983) J.Clin. Immunology 3: 332; Flomenberg, N., et al. (1983) J. Immunol. 130:2644).

Other factors, which could have been reasons for defective IL2production by PBMC include: (a) the quality or quantity of transplantedT lymphocytes and their precursors, (b) the conditioning for thetransplantation with alteration of the microenvironment by chemotherapyand irradiation, (c) post-transplant immunosuppression (prednisone,methotrexate), (d) T cell maturation defects following the absence of anormal thymic milieu (a-d have also been proposed as possibly causingthe low OKT4/OKT8 ratio; (Schroff, R. W., (1982) 129: 1926)), (e) adefective interaction between Ia+monocytes/macrophages and T cells.Since similar defective OKT3 mitogen responses were seen followingautologous and allogeneic BMT, it appears unlikely thathistocompatibility differences or post-transplant immunosuppressivetherapy were responsible for the defects. Furthermore, patientsreceiving (a) no conditioning regiment or (b) chemotherapy with orwithout TBI, showed the same defects with respect to OKT3 mitogenresponses. Although several of the agents given to BMT patients havepreviously been shown to suppress IL2 production and response by PBL(e.g. cyclophosphamide, (Merluzzi (1983) J. Immunol. 131: 806);cyclosporine A, (Hess. A. D. et al. (1982) J. Immunol. 128: 355)), noclear relationship between administration of these drugs and defectiveOKT3 mitogen responses was observed. These observations would suggestthat defects in T cell function following BMT were primarily due to thequality or quantity of transplanted T lymphocytes or their precursors.This hypothesis is in agreement with previous reports demonstratingrelative immaturity of T lymphocytes in BMT patients [deBruin, H. G.,eet al. (1981) J. Immunol. 127: 244; Fox. R., et al. (1982) Blood 60:578; Schroff, R. W. et al. (1982) J. Immunol. 129: 1926].

As expected, the defective IL2 production was followed by defectiveproliferation of PBMC as measured by ³ H-thymidine incorporation. In thefirst 6 months after BMT, PBMC from all patients but one exhibiteddefective mitogen responses to OKT3. In the group 7-18 months after BMT,PBMC from 3 of 8 patients showed normal proliferative responses. In thepresence of hpIL2(10 U/ml), proliferative responses of PBMC to OKT3antibody could be restored to within the normal range in all but threepatients. One of these three patients received cyclosporin A at the timeof study. However, this PBMC proliferation improved from 1,100 cpm inthe absence of IL2 to 13,000 cpm in the presence of IL2. PBMC from thetwo other patients showed normal proliferation upon addition of hpIL2two months after the first study. Whether different kinetics ofrestoration of IL2 production and T cell proliferation after BMT are ofprognostic value, is under investigation.

The finding that OKT3 antibody was a potent mitogen raised thepossibility that OKT3 antibody was reacting with the antigen recognitioncomplex of T cells [Chang, T. W., et al. (1981) Proc. Nat'l. Acad. Sci.USA. 78: 1805; Reinherz, E. L., et al. (1982) Cell 30: 735] triggeringmitogenesis in a way similar to that induced by antigen. The percentageof OKT3 positive lymphocytes reaches normal values shortly aftertransplantation in most patients and remains normal thereafter in allpatients [deBruin, H. G., et al. (1981) J. Immunol. 127: 244; Friedrich,W., et al. (1982) Blood 59: 696; Fox, R., et al. (1982) Blood 60: 678].Possible induction of OKT3 antigen by IL2 is therefore an unlikelyexplanation for the IL2 responsiveness of OKT3 antibody stimulated PBMC.Furthermore, OKT3 antibody induces modulation of OKT3 antigen, which maybe part of the mitogenic effect of OKT3 antibody, within a few hours(Reinherz, E. L., et al. (1982) Cell 30: 735; E. Rinnooy Kan, E.Platzer, K., Welte, C. Y. Wang, submitted for publication). TheOKT3antigen modulation, however, does not render cells unresponsive toIL2 (Welte, K., et al. (1983) J. Immunol. 131: 2356; Reinherz, E. L., etal. (1982) Cell 30: 735).

The OKT3antibody induced proliferation of PBMC was normalized in vitroin nearly all patients by hpIL2, whereas only 4 patients achievednormalization of their proliferative response of PBL upon addition ofhpIL2 with PHA as mitogen. This observation would suggest that Tlymphocytes in patients after BMT were able to express normal levels ofIL2 receptors in response to OKT3 antibody but not to PHA. IL2 haspreviously been shown to be able to restore (a) impaired cell-mediatedlympholysis in patients with acute GvHD but not chronic GvHD [Mori, T.,et al. (1983) J. Immunol. 130: 712] and (b) PHA stimulated T cellcolony-formation of lymphocytes from patients early after BMT(Donnenberg, A. D., et al. (1982) J. Immunol. 129: 1080). Both groupshypothesized, that the defect in those patients was a functional Thelper cell defect. Both reports are consistent with our observations,that T cells from patients after BMT were capable of responding to IL2.

Since defective IL2 production and correction of functional T celldefects in vitro by hpIL2 have now been well documented in patientsafter BMT, in vivo administration of IL2 might be beneficial for thesepatients. In our ongoing phase I trial of hpIL2 in patients with otherimmunodeficiency states (AIDs, lymphoma) no side effects have been seenat up to 20,000 U/m² for 14 days [Mertelsman, R., et al. (1983)Proceedings of the UCLA Symposia on Molecular and Cellular Biology,Steamboat Springs 1983 (in press)]. However, in patients after BMT IL2might enhance or cause acute GvHD. Animal studies have been initiated toaddress this problem.

What is claimed:
 1. Native highly purified human IL-2 wherein said IL-2is obtained from normal peripheral lymphocytes is purified over 37,000fold and exhibits pharmacological activity in humans and has a specificactivity of at least 10⁶ ±10% U/mg and a threshold concentration forbiological activity no greater than 0.2±0.05 U/ml and wherein the IL-2:(1) has a relative molecular weight of 26000±4000 daltons with anisoelectric point of pH 6.7±0.2 when produced in the absence of Daudicells which IL-2 material when denatured exhibits a relative molecularweight of 16,000±1,000 or 17,000±1,000 daltons,(2) has a relativemolecular weight of 14,500±2000 daltons with an isoelectric point of pH8.1±0.02 when produced in the presence of Daudi cells, (3) is pyrogenfree, (4) is free of contaminants selected from the group consisting ofB-cell growth factor (BGF), B-cell inducing factor (BIF), alpha or gammainterferon (IFN), granulocyte-macrophage colony-stimulating factor (CSF)and thymocyte differentiating activity, and (5) is free of proteinaceouscontaminant when assayed by the silver nitrate or I¹²⁵ exolabelingmethods.